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What Is A Research Hypothesis?

A Plain-Language Explainer + Practical Examples

Research Hypothesis 101

• What is a hypothesis ?
• What is a research hypothesis (scientific hypothesis)?
• Requirements for a research hypothesis
• Definition of a research hypothesis
• The null hypothesis

What is a hypothesis?

Let’s start with the general definition of a hypothesis (not a research hypothesis or scientific hypothesis), according to the Cambridge Dictionary:

Hypothesis: an idea or explanation for something that is based on known facts but has not yet been proved.

In other words, it’s a statement that provides an explanation for why or how something works, based on facts (or some reasonable assumptions), but that has not yet been specifically tested . For example, a hypothesis might look something like this:

Hypothesis: sleep impacts academic performance.

This statement predicts that academic performance will be influenced by the amount and/or quality of sleep a student engages in – sounds reasonable, right? It’s based on reasonable assumptions , underpinned by what we currently know about sleep and health (from the existing literature). So, loosely speaking, we could call it a hypothesis, at least by the dictionary definition.

But that’s not good enough…

Unfortunately, that’s not quite sophisticated enough to describe a research hypothesis (also sometimes called a scientific hypothesis), and it wouldn’t be acceptable in a dissertation, thesis or research paper . In the world of academic research, a statement needs a few more criteria to constitute a true research hypothesis .

What is a research hypothesis?

A research hypothesis (also called a scientific hypothesis) is a statement about the expected outcome of a study (for example, a dissertation or thesis). To constitute a quality hypothesis, the statement needs to have three attributes – specificity , clarity and testability .

Let’s take a look at these more closely.

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Hypothesis Essential #1: Specificity & Clarity

A good research hypothesis needs to be extremely clear and articulate about both what’ s being assessed (who or what variables are involved ) and the expected outcome (for example, a difference between groups, a relationship between variables, etc.).

Let’s stick with our sleepy students example and look at how this statement could be more specific and clear.

Hypothesis: Students who sleep at least 8 hours per night will, on average, achieve higher grades in standardised tests than students who sleep less than 8 hours a night.

As you can see, the statement is very specific as it identifies the variables involved (sleep hours and test grades), the parties involved (two groups of students), as well as the predicted relationship type (a positive relationship). There’s no ambiguity or uncertainty about who or what is involved in the statement, and the expected outcome is clear.

Contrast that to the original hypothesis we looked at – “Sleep impacts academic performance” – and you can see the difference. “Sleep” and “academic performance” are both comparatively vague , and there’s no indication of what the expected relationship direction is (more sleep or less sleep). As you can see, specificity and clarity are key.

Hypothesis Essential #2: Testability (Provability)

A statement must be testable to qualify as a research hypothesis. In other words, there needs to be a way to prove (or disprove) the statement. If it’s not testable, it’s not a hypothesis – simple as that.

For example, consider the hypothesis we mentioned earlier:

We could test this statement by undertaking a quantitative study involving two groups of students, one that gets 8 or more hours of sleep per night for a fixed period, and one that gets less. We could then compare the standardised test results for both groups to see if there’s a statistically significant difference.

Again, if you compare this to the original hypothesis we looked at – “Sleep impacts academic performance” – you can see that it would be quite difficult to test that statement, primarily because it isn’t specific enough. How much sleep? By who? What type of academic performance?

So, remember the mantra – if you can’t test it, it’s not a hypothesis 🙂

Defining A Research Hypothesis

You’re still with us? Great! Let’s recap and pin down a clear definition of a hypothesis.

A research hypothesis (or scientific hypothesis) is a statement about an expected relationship between variables, or explanation of an occurrence, that is clear, specific and testable.

So, when you write up hypotheses for your dissertation or thesis, make sure that they meet all these criteria. If you do, you’ll not only have rock-solid hypotheses but you’ll also ensure a clear focus for your entire research project.

What about the null hypothesis?

You may have also heard the terms null hypothesis , alternative hypothesis, or H-zero thrown around. At a simple level, the null hypothesis is the counter-proposal to the original hypothesis.

For example, if the hypothesis predicts that there is a relationship between two variables (for example, sleep and academic performance), the null hypothesis would predict that there is no relationship between those variables.

At a more technical level, the null hypothesis proposes that no statistical significance exists in a set of given observations and that any differences are due to chance alone.

And there you have it – hypotheses in a nutshell. 

If you have any questions, be sure to leave a comment below and we’ll do our best to help you. If you need hands-on help developing and testing your hypotheses, consider our private coaching service , where we hold your hand through the research journey.

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18 Comments

Very useful information. I benefit more from getting more information in this regard.

Very great insight,educative and informative. Please give meet deep critics on many research data of public international Law like human rights, environment, natural resources, law of the sea etc

In a book I read a distinction is made between null, research, and alternative hypothesis. As far as I understand, alternative and research hypotheses are the same. Can you please elaborate? Best Afshin

This is a self explanatory, easy going site. I will recommend this to my friends and colleagues.

Very good definition. How can I cite your definition in my thesis? Thank you. Is nul hypothesis compulsory in a research?

It’s a counter-proposal to be proven as a rejection

Please what is the difference between alternate hypothesis and research hypothesis?

It is a very good explanation. However, it limits hypotheses to statistically tasteable ideas. What about for qualitative researches or other researches that involve quantitative data that don’t need statistical tests?

In qualitative research, one typically uses propositions, not hypotheses.

could you please elaborate it more

I’ve benefited greatly from these notes, thank you.

This is very helpful

well articulated ideas are presented here, thank you for being reliable sources of information

Excellent. Thanks for being clear and sound about the research methodology and hypothesis (quantitative research)

I have only a simple question regarding the null hypothesis. – Is the null hypothesis (Ho) known as the reversible hypothesis of the alternative hypothesis (H1? – How to test it in academic research?

Angelo Loye Very fantastic information. From here I am going straightaway to present the research hypothesis One question, do we apply hypothesis in qualitative research? What nul hypothesi Otherwise I appreciate your research methodo

this is very important note help me much more

Hi” best wishes to you and your very nice blog” 

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How to Write a Great Hypothesis

Hypothesis Definition, Format, Examples, and Tips

Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Amy Morin, LCSW, is a psychotherapist and international bestselling author. Her books, including "13 Things Mentally Strong People Don't Do," have been translated into more than 40 languages. Her TEDx talk,  "The Secret of Becoming Mentally Strong," is one of the most viewed talks of all time.

Verywell / Alex Dos Diaz

• The Scientific Method

Hypothesis Format

Falsifiability of a hypothesis.

• Operationalization

Hypothesis Types

Hypotheses examples.

• Collecting Data

A hypothesis is a tentative statement about the relationship between two or more variables. It is a specific, testable prediction about what you expect to happen in a study. It is a preliminary answer to your question that helps guide the research process.

Consider a study designed to examine the relationship between sleep deprivation and test performance. The hypothesis might be: "This study is designed to assess the hypothesis that sleep-deprived people will perform worse on a test than individuals who are not sleep-deprived."

At a Glance

A hypothesis is crucial to scientific research because it offers a clear direction for what the researchers are looking to find. This allows them to design experiments to test their predictions and add to our scientific knowledge about the world. This article explores how a hypothesis is used in psychology research, how to write a good hypothesis, and the different types of hypotheses you might use.

The Hypothesis in the Scientific Method

In the scientific method , whether it involves research in psychology, biology, or some other area, a hypothesis represents what the researchers think will happen in an experiment. The scientific method involves the following steps:

• Forming a question
• Performing background research
• Creating a hypothesis
• Designing an experiment
• Collecting data
• Analyzing the results
• Drawing conclusions
• Communicating the results

The hypothesis is a prediction, but it involves more than a guess. Most of the time, the hypothesis begins with a question which is then explored through background research. At this point, researchers then begin to develop a testable hypothesis.

Unless you are creating an exploratory study, your hypothesis should always explain what you  expect  to happen.

In a study exploring the effects of a particular drug, the hypothesis might be that researchers expect the drug to have some type of effect on the symptoms of a specific illness. In psychology, the hypothesis might focus on how a certain aspect of the environment might influence a particular behavior.

Remember, a hypothesis does not have to be correct. While the hypothesis predicts what the researchers expect to see, the goal of the research is to determine whether this guess is right or wrong. When conducting an experiment, researchers might explore numerous factors to determine which ones might contribute to the ultimate outcome.

In many cases, researchers may find that the results of an experiment  do not  support the original hypothesis. When writing up these results, the researchers might suggest other options that should be explored in future studies.

In many cases, researchers might draw a hypothesis from a specific theory or build on previous research. For example, prior research has shown that stress can impact the immune system. So a researcher might hypothesize: "People with high-stress levels will be more likely to contract a common cold after being exposed to the virus than people who have low-stress levels."

In other instances, researchers might look at commonly held beliefs or folk wisdom. "Birds of a feather flock together" is one example of folk adage that a psychologist might try to investigate. The researcher might pose a specific hypothesis that "People tend to select romantic partners who are similar to them in interests and educational level."

Elements of a Good Hypothesis

So how do you write a good hypothesis? When trying to come up with a hypothesis for your research or experiments, ask yourself the following questions:

• Is your hypothesis based on your research on a topic?
• Can your hypothesis be tested?
• Does your hypothesis include independent and dependent variables?

Before you come up with a specific hypothesis, spend some time doing background research. Once you have completed a literature review, start thinking about potential questions you still have. Pay attention to the discussion section in the  journal articles you read . Many authors will suggest questions that still need to be explored.

How to Formulate a Good Hypothesis

To form a hypothesis, you should take these steps:

• Collect as many observations about a topic or problem as you can.
• Evaluate these observations and look for possible causes of the problem.
• Create a list of possible explanations that you might want to explore.
• After you have developed some possible hypotheses, think of ways that you could confirm or disprove each hypothesis through experimentation. This is known as falsifiability.

In the scientific method ,  falsifiability is an important part of any valid hypothesis. In order to test a claim scientifically, it must be possible that the claim could be proven false.

Students sometimes confuse the idea of falsifiability with the idea that it means that something is false, which is not the case. What falsifiability means is that  if  something was false, then it is possible to demonstrate that it is false.

One of the hallmarks of pseudoscience is that it makes claims that cannot be refuted or proven false.

The Importance of Operational Definitions

A variable is a factor or element that can be changed and manipulated in ways that are observable and measurable. However, the researcher must also define how the variable will be manipulated and measured in the study.

Operational definitions are specific definitions for all relevant factors in a study. This process helps make vague or ambiguous concepts detailed and measurable.

For example, a researcher might operationally define the variable " test anxiety " as the results of a self-report measure of anxiety experienced during an exam. A "study habits" variable might be defined by the amount of studying that actually occurs as measured by time.

These precise descriptions are important because many things can be measured in various ways. Clearly defining these variables and how they are measured helps ensure that other researchers can replicate your results.

Replicability

One of the basic principles of any type of scientific research is that the results must be replicable.

Replication means repeating an experiment in the same way to produce the same results. By clearly detailing the specifics of how the variables were measured and manipulated, other researchers can better understand the results and repeat the study if needed.

Some variables are more difficult than others to define. For example, how would you operationally define a variable such as aggression ? For obvious ethical reasons, researchers cannot create a situation in which a person behaves aggressively toward others.

To measure this variable, the researcher must devise a measurement that assesses aggressive behavior without harming others. The researcher might utilize a simulated task to measure aggressiveness in this situation.

Hypothesis Checklist

• Does your hypothesis focus on something that you can actually test?
• Does your hypothesis include both an independent and dependent variable?
• Can you manipulate the variables?
• Can your hypothesis be tested without violating ethical standards?

The hypothesis you use will depend on what you are investigating and hoping to find. Some of the main types of hypotheses that you might use include:

• Simple hypothesis : This type of hypothesis suggests there is a relationship between one independent variable and one dependent variable.
• Complex hypothesis : This type suggests a relationship between three or more variables, such as two independent and dependent variables.
• Null hypothesis : This hypothesis suggests no relationship exists between two or more variables.
• Alternative hypothesis : This hypothesis states the opposite of the null hypothesis.
• Statistical hypothesis : This hypothesis uses statistical analysis to evaluate a representative population sample and then generalizes the findings to the larger group.
• Logical hypothesis : This hypothesis assumes a relationship between variables without collecting data or evidence.

A hypothesis often follows a basic format of "If {this happens} then {this will happen}." One way to structure your hypothesis is to describe what will happen to the  dependent variable  if you change the  independent variable .

The basic format might be: "If {these changes are made to a certain independent variable}, then we will observe {a change in a specific dependent variable}."

A few examples of simple hypotheses:

• "Students who eat breakfast will perform better on a math exam than students who do not eat breakfast."
• "Students who experience test anxiety before an English exam will get lower scores than students who do not experience test anxiety."​
• "Motorists who talk on the phone while driving will be more likely to make errors on a driving course than those who do not talk on the phone."
• "Children who receive a new reading intervention will have higher reading scores than students who do not receive the intervention."

Examples of a complex hypothesis include:

• "People with high-sugar diets and sedentary activity levels are more likely to develop depression."
• "Younger people who are regularly exposed to green, outdoor areas have better subjective well-being than older adults who have limited exposure to green spaces."

Examples of a null hypothesis include:

• "There is no difference in anxiety levels between people who take St. John's wort supplements and those who do not."
• "There is no difference in scores on a memory recall task between children and adults."
• "There is no difference in aggression levels between children who play first-person shooter games and those who do not."

Examples of an alternative hypothesis:

• "People who take St. John's wort supplements will have less anxiety than those who do not."
• "Adults will perform better on a memory task than children."
• "Children who play first-person shooter games will show higher levels of aggression than children who do not." 

Collecting Data on Your Hypothesis

Once a researcher has formed a testable hypothesis, the next step is to select a research design and start collecting data. The research method depends largely on exactly what they are studying. There are two basic types of research methods: descriptive research and experimental research.

Descriptive Research Methods

Descriptive research such as  case studies ,  naturalistic observations , and surveys are often used when  conducting an experiment is difficult or impossible. These methods are best used to describe different aspects of a behavior or psychological phenomenon.

Once a researcher has collected data using descriptive methods, a  correlational study  can examine how the variables are related. This research method might be used to investigate a hypothesis that is difficult to test experimentally.

Experimental Research Methods

Experimental methods  are used to demonstrate causal relationships between variables. In an experiment, the researcher systematically manipulates a variable of interest (known as the independent variable) and measures the effect on another variable (known as the dependent variable).

Unlike correlational studies, which can only be used to determine if there is a relationship between two variables, experimental methods can be used to determine the actual nature of the relationship—whether changes in one variable actually  cause  another to change.

The hypothesis is a critical part of any scientific exploration. It represents what researchers expect to find in a study or experiment. In situations where the hypothesis is unsupported by the research, the research still has value. Such research helps us better understand how different aspects of the natural world relate to one another. It also helps us develop new hypotheses that can then be tested in the future.

Thompson WH, Skau S. On the scope of scientific hypotheses .  R Soc Open Sci . 2023;10(8):230607. doi:10.1098/rsos.230607

Taran S, Adhikari NKJ, Fan E. Falsifiability in medicine: what clinicians can learn from Karl Popper [published correction appears in Intensive Care Med. 2021 Jun 17;:].  Intensive Care Med . 2021;47(9):1054-1056. doi:10.1007/s00134-021-06432-z

Eyler AA. Research Methods for Public Health . 1st ed. Springer Publishing Company; 2020. doi:10.1891/9780826182067.0004

Nosek BA, Errington TM. What is replication ?  PLoS Biol . 2020;18(3):e3000691. doi:10.1371/journal.pbio.3000691

Aggarwal R, Ranganathan P. Study designs: Part 2 - Descriptive studies .  Perspect Clin Res . 2019;10(1):34-36. doi:10.4103/picr.PICR_154_18

Nevid J. Psychology: Concepts and Applications. Wadworth, 2013.

By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

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Home » What is a Hypothesis – Types, Examples and Writing Guide

What is a Hypothesis – Types, Examples and Writing Guide

Table of Contents

In research, a hypothesis is a clear, testable statement predicting the relationship between variables or the outcome of a study. Hypotheses form the foundation of scientific inquiry, providing a direction for investigation and guiding the data collection and analysis process. Hypotheses are typically used in quantitative research but can also inform some qualitative studies by offering a preliminary assumption about the subject being explored.

A hypothesis is a specific, testable prediction or statement that suggests an expected relationship between variables in a study. It acts as a starting point, guiding researchers to examine whether their predictions hold true based on collected data. For a hypothesis to be useful, it must be clear, concise, and based on prior knowledge or theoretical frameworks.

Key Characteristics of a Hypothesis :

• Testable : Must be possible to evaluate or observe the outcome through experimentation or analysis.
• Specific : Clearly defines variables and the expected relationship or outcome.
• Predictive : States an anticipated effect or association that can be confirmed or refuted.

Example : “Increasing the amount of daily physical exercise will lead to a reduction in stress levels among college students.”

Types of Hypotheses

Hypotheses can be categorized into several types, depending on their structure, purpose, and the type of relationship they suggest. The most common types include null hypothesis , alternative hypothesis , directional hypothesis , and non-directional hypothesis .

1. Null Hypothesis (H₀)

Definition : The null hypothesis states that there is no relationship between the variables being studied or that any observed effect is due to chance. It serves as the default position, which researchers aim to test against to determine if a significant effect or association exists.

Purpose : To provide a baseline that can be statistically tested to verify if a relationship or difference exists.

Example : “There is no difference in academic performance between students who receive additional tutoring and those who do not.”

2. Alternative Hypothesis (H₁ or Hₐ)

Definition : The alternative hypothesis proposes that there is a relationship or effect between variables. This hypothesis contradicts the null hypothesis and suggests that any observed result is not due to chance.

Purpose : To present an expected outcome that researchers aim to support with data.

Example : “Students who receive additional tutoring will perform better academically than those who do not.”

3. Directional Hypothesis

Definition : A directional hypothesis specifies the direction of the expected relationship between variables, predicting either an increase, decrease, positive, or negative effect.

Purpose : To provide a more precise prediction by indicating the expected direction of the relationship.

Example : “Increasing the duration of daily exercise will lead to a decrease in stress levels among adults.”

4. Non-Directional Hypothesis

Definition : A non-directional hypothesis states that there is a relationship between variables but does not specify the direction of the effect.

Purpose : To allow for exploration of the relationship without committing to a particular direction.

Example : “There is a difference in stress levels between adults who exercise regularly and those who do not.”

Examples of Hypotheses in Different Fields

• Null Hypothesis : “There is no difference in anxiety levels between individuals who practice mindfulness and those who do not.”
• Alternative Hypothesis : “Individuals who practice mindfulness will report lower anxiety levels than those who do not.”
• Directional Hypothesis : “Providing feedback will improve students’ motivation to learn.”
• Non-Directional Hypothesis : “There is a difference in motivation levels between students who receive feedback and those who do not.”
• Null Hypothesis : “There is no association between diet and energy levels among teenagers.”
• Alternative Hypothesis : “A balanced diet is associated with higher energy levels among teenagers.”
• Directional Hypothesis : “An increase in employee engagement activities will lead to improved job satisfaction.”
• Non-Directional Hypothesis : “There is a relationship between employee engagement activities and job satisfaction.”
• Null Hypothesis : “The introduction of green spaces does not affect urban air quality.”
• Alternative Hypothesis : “Green spaces improve urban air quality.”

Writing Guide for Hypotheses

Writing a clear, testable hypothesis involves several steps, starting with understanding the research question and selecting variables. Here’s a step-by-step guide to writing an effective hypothesis.

Step 1: Identify the Research Question

Start by defining the primary research question you aim to investigate. This question should be focused, researchable, and specific enough to allow for hypothesis formation.

Example : “Does regular physical exercise improve mental well-being in college students?”

Step 2: Conduct Background Research

Review relevant literature to gain insight into existing theories, studies, and gaps in knowledge. This helps you understand prior findings and guides you in forming a logical hypothesis based on evidence.

Example : Research shows a positive correlation between exercise and mental well-being, which supports forming a hypothesis in this area.

Step 3: Define the Variables

Identify the independent and dependent variables. The independent variable is the factor you manipulate or consider as the cause, while the dependent variable is the outcome or effect you are measuring.

• Independent Variable : Amount of physical exercise
• Dependent Variable : Mental well-being (measured through self-reported stress levels)

Step 4: Choose the Hypothesis Type

Select the hypothesis type based on the research question. If you predict a specific outcome or direction, use a directional hypothesis. If not, a non-directional hypothesis may be suitable.

Example : “Increasing the frequency of physical exercise will reduce stress levels among college students” (directional hypothesis).

Step 5: Write the Hypothesis

Formulate the hypothesis as a clear, concise statement. Ensure it is specific, testable, and focuses on the relationship between the variables.

Example : “College students who exercise at least three times per week will report lower stress levels than those who do not exercise regularly.”

Step 6: Test and Refine (Optional)

In some cases, it may be necessary to refine the hypothesis after conducting a preliminary test or pilot study. This ensures that your hypothesis is realistic and feasible within the study parameters.

Tips for Writing an Effective Hypothesis

• Use Clear Language : Avoid jargon or ambiguous terms to ensure your hypothesis is easily understandable.
• Be Specific : Specify the expected relationship between the variables, and, if possible, include the direction of the effect.
• Ensure Testability : Frame the hypothesis in a way that allows for empirical testing or observation.
• Focus on One Relationship : Avoid complexity by focusing on a single, clear relationship between variables.
• Make It Measurable : Choose variables that can be quantified or observed to simplify data collection and analysis.

Common Mistakes to Avoid

• Vague Statements : Avoid vague hypotheses that don’t specify a clear relationship or outcome.
• Unmeasurable Variables : Ensure that the variables in your hypothesis can be observed, measured, or quantified.
• Overly Complex Hypotheses : Keep the hypothesis simple and focused, especially for beginner researchers.
• Using Personal Opinions : Avoid subjective or biased language that could impact the neutrality of the hypothesis.

Examples of Well-Written Hypotheses

• Psychology : “Adolescents who spend more than two hours on social media per day will report higher levels of anxiety than those who spend less than one hour.”
• Business : “Increasing customer service training will improve customer satisfaction ratings among retail employees.”
• Health : “Consuming a diet rich in fruits and vegetables is associated with lower cholesterol levels in adults.”
• Education : “Students who participate in active learning techniques will have higher retention rates compared to those in traditional lecture-based classrooms.”
• Environmental Science : “Urban areas with more green spaces will report lower average temperatures than those with minimal green coverage.”

A well-formulated hypothesis is essential to the research process, providing a clear and testable prediction about the relationship between variables. Understanding the different types of hypotheses, following a structured writing approach, and avoiding common pitfalls help researchers create hypotheses that effectively guide data collection, analysis, and conclusions. Whether working in psychology, education, health sciences, or any other field, an effective hypothesis sharpens the focus of a study and enhances the rigor of research.

• Creswell, J. W., & Creswell, J. D. (2018). Research Design: Qualitative, Quantitative, and Mixed Methods Approaches (5th ed.). SAGE Publications.
• Field, A. (2013). Discovering Statistics Using IBM SPSS Statistics (4th ed.). SAGE Publications.
• Trochim, W. M. K. (2006). The Research Methods Knowledge Base (3rd ed.). Atomic Dog Publishing.
• McLeod, S. A. (2019). What is a Hypothesis? Retrieved from https://www.simplypsychology.org/what-is-a-hypotheses.html
• Walliman, N. (2017). Research Methods: The Basics (2nd ed.). Routledge.

About the author

Muhammad Hassan

Researcher, Academic Writer, Web developer

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• How to Write a Strong Hypothesis | Guide & Examples

How to Write a Strong Hypothesis | Guide & Examples

Published on 6 May 2022 by Shona McCombes .

A hypothesis is a statement that can be tested by scientific research. If you want to test a relationship between two or more variables, you need to write hypotheses before you start your experiment or data collection.

Table of contents

What is a hypothesis, developing a hypothesis (with example), hypothesis examples, frequently asked questions about writing hypotheses.

A hypothesis states your predictions about what your research will find. It is a tentative answer to your research question that has not yet been tested. For some research projects, you might have to write several hypotheses that address different aspects of your research question.

A hypothesis is not just a guess – it should be based on existing theories and knowledge. It also has to be testable, which means you can support or refute it through scientific research methods (such as experiments, observations, and statistical analysis of data).

Variables in hypotheses

Hypotheses propose a relationship between two or more variables . An independent variable is something the researcher changes or controls. A dependent variable is something the researcher observes and measures.

In this example, the independent variable is exposure to the sun – the assumed cause . The dependent variable is the level of happiness – the assumed effect .

Prevent plagiarism, run a free check.

Step 1: ask a question.

Writing a hypothesis begins with a research question that you want to answer. The question should be focused, specific, and researchable within the constraints of your project.

Step 2: Do some preliminary research

Your initial answer to the question should be based on what is already known about the topic. Look for theories and previous studies to help you form educated assumptions about what your research will find.

At this stage, you might construct a conceptual framework to identify which variables you will study and what you think the relationships are between them. Sometimes, you’ll have to operationalise more complex constructs.

Step 3: Formulate your hypothesis

Now you should have some idea of what you expect to find. Write your initial answer to the question in a clear, concise sentence.

Step 4: Refine your hypothesis

You need to make sure your hypothesis is specific and testable. There are various ways of phrasing a hypothesis, but all the terms you use should have clear definitions, and the hypothesis should contain:

• The relevant variables
• The specific group being studied
• The predicted outcome of the experiment or analysis

Step 5: Phrase your hypothesis in three ways

To identify the variables, you can write a simple prediction in if … then form. The first part of the sentence states the independent variable and the second part states the dependent variable.

In academic research, hypotheses are more commonly phrased in terms of correlations or effects, where you directly state the predicted relationship between variables.

If you are comparing two groups, the hypothesis can state what difference you expect to find between them.

Step 6. Write a null hypothesis

If your research involves statistical hypothesis testing , you will also have to write a null hypothesis. The null hypothesis is the default position that there is no association between the variables. The null hypothesis is written as H 0 , while the alternative hypothesis is H 1 or H a .

Hypothesis testing is a formal procedure for investigating our ideas about the world using statistics. It is used by scientists to test specific predictions, called hypotheses , by calculating how likely it is that a pattern or relationship between variables could have arisen by chance.

A hypothesis is not just a guess. It should be based on existing theories and knowledge. It also has to be testable, which means you can support or refute it through scientific research methods (such as experiments, observations, and statistical analysis of data).

A research hypothesis is your proposed answer to your research question. The research hypothesis usually includes an explanation (‘ x affects y because …’).

A statistical hypothesis, on the other hand, is a mathematical statement about a population parameter. Statistical hypotheses always come in pairs: the null and alternative hypotheses. In a well-designed study , the statistical hypotheses correspond logically to the research hypothesis.

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How to Write a Hypothesis: The Ultimate Guide with Examples

Hypotheses aren’t about science, experiments, and creating new theories only. While students in science classes formulate a hypothesis every second day, others from non-science fields may find it challenging to write it for an essay or a research paper.

This article is here to reveal the nature of hypothesis writing and help you learn how to write a hypothesis for essays, reports, studies, and any paper type you may need to compose.

We’ve researched all the guides, invited  our top writers  to answer all the FAQs students have on hypothesis writing, gathered hypothesis examples, and put first things first.

Yes, we are ready to make it loud and clear with our essay maker !

Table of Contents:

• Hypothesis vs. prediction
• Theory vs. hypothesis
• Hypothesis characteristics
• Thesis statement vs. hypothesis in an essay
• Main hypothesis sources
• 7 types of hypotheses you may need to write
• Ask a question
• Conduct research
• Write a null hypothesis
• Define variables
• State it using an if-then format
• What is a hypothesis in a research paper?
• How to write a hypothesis: example
• Frequently asked questions

What is a Hypothesis?

A hypothesis is an assumption you make based on existing data and knowledge, stating your predictions about what your research will find. It’s a tentative answer to your research question; it needs to be testable so you could later support or refuse it through further experiments, observations, and any other scientific research methods.

Example of a hypothesis:

Teenagers who get sex education lessons in high school will have lower rates of unplanned pregnancy than those who did not get any sex education.

Your research question here is,  “How effective is high school sex education at reducing teen pregnancies?”  and you formulate a hypothesis to check and explain in your paper.

A hypothesis always proposes a relationship between several variables. As a rule, variables are two – independent and dependent – but it’s also possible to state more variables in your hypothesis essay, to address different aspects of your research question.

• An independent variable  is the one you, as a researcher, can change or control.
• A dependent variable  is the one you, as a researcher, observe and measure based on how an independent variable changes.

In the above example, we can see that an independent variable is “sex education lessons at school” (you assume it is a cause). And a dependent variable here is “lower rates of unplanned pregnancy” (you consider it’s an effect).

Please note that there’s a difference between theory and hypothesis. Also, some guides may tell you that a hypothesis equals a  thesis statement  in essay writing, though a slight difference between these two is yet in place.

More on that below.

Hypothesis vs. Prediction

Given they both are a kind of guess, many people get a hypothesis and a prediction confused. But while a difference is slight, it’s yet critical:

• A hypothesis  explains  why something happens based on  scientific methods  (testing, experiments, data analysis, etc.).
• A prediction  suggests  that something will happen based on  observations .

You write a hypothesis using a statement with variables, while a prediction consists of “if-then” schemes stating about future happenings.

We can also say that a prediction is something you expect to happen if your hypothesis statement is true.

Theory vs. Hypothesis

• A hypothesis states a  suggested  explanation of a phenomenon, which you’ll later support or refuse through testing and other scientific methods.
• A theory is an  already tested , well-substantiated explanation backed by evidence.

You write a hypothesis using a statement with variables, while a theory represents a phenomenon that is already widely accepted and supported by data.

Examples of theories include Einstein’s theory of relativity, the Big Bang theory, Charles Darwin’s theory of evolution, and many others.

For your hypothesis to become a theory, you need to test all the aspects under various circumstances and prove it with well-substantiated facts. You can also use theories to make predictions about something unexplained and then turn those predictions into hypotheses to test and support (or refuse).

It’s worth noting that testings don’t stop once a hypothesis becomes a theory: Science is ongoing, and any theory can become disproved one day.

Hypothesis Characteristics

And now it’s high time to reveal the characteristics of your statement to become a reasonable hypothesis.

They are five:

• A cause-effect relationship between variables . When writing a hypothesis, make sure your one variable causes another one to change (or not change.) There should always be a cause-effect relationship between them.
• Testable nature.  Formulate a hypothesis that you can  test  to support or refuse. You should be able to conduct experiments and control your thesis when working on it.
• Precise and accurate variables.  Your hypothesis’s independent and dependent variables need to be specific and clear for the audience to understand.
• Explained in simple language.   Research papers  and academic writing, in general, are often challenging to understand for an average reader, so do your best to write a hypothesis so there would be no confusion or ambiguity.
• Ethical.  We can test many things, but there’s always a question about  what  we should test or make a subject to experiments. Avoid questionable or taboo topics when thinking about your hypothesis outline.

Thesis Statement vs. Hypothesis in an Essay

When looking for information on writing a hypothesis essay, you can find guides telling that it’s the same with writing a thesis statement for your  argumentative essay . This notion is not entirely true, and there’s still a slight difference between these two:

• A thesis statement is a sentence or two in your essay introduction that summarizes a central claim you’ll  discuss and prove  in the essay body. You’ll use arguments, evidence, and examples for that. 
• A hypothesis is a one-sentence prediction based on the relationships between reliables that you’ll  test   and then  prove or disprove  in the essay body. You’ll use experiments, observation, and quantitative research for that.

Writing a research study should have a thesis statement; if your research intends to prove/disprove something, it will also contain a hypothesis statement.

Feel free to try our  online thesis statement generator  to get a better idea of writing strong thesis statements for your essays.

Main Hypothesis Sources

Once they ask you to write a hypothesis essay, it would be great to have some sources for inspiration at hand, wouldn’t it?

Where to go for  creative ideas ? Where to research hypothesis and come up with new statements for your essay? What sources do science students use?

The primary hypothesis sources are four:

• Scientific theories that already exist
• Some general patterns affecting our thinking process
• Analogies between different phenomena we observe
• The previous knowledge and observations from studies and our experience

Depending on the niche and type of hypothesis you need to cover, you’ll use corresponding sources for research and further hypothesis  outline .

Below you’ll learn what types of hypotheses exist and how to write a hypothesis statement so it would sound scientific.

7 Types of Hypotheses You May Need to Write

So many sources, so many hypothesis classifications they offer. Some specify eight, ten, and even 13  types of hypotheses, depending on the factors like the number of variables you use and the experiment stage you’re in. Some insist that only two significant kinds of hypotheses exist: alternative and null; others call them directional and non-directional hypotheses, respectively.

Let’s put things straight and explain the types of hypotheses you may need to write in essays . They are seven, with examples for you to get a better idea of “who is who,” as they say.

1) Simple hypothesis

It’s the most common type of hypothesis to use in college papers, predicting the direct relationship between two variables in your experiment: a single dependent and a single independent one.

How to write a simple hypothesis? Use an “if-then” format.

For example:

• Everyday smoking leads to lung cancer.  ( If  you smoke every day,  then  you’ll get lung cancer.)
• Covering wounds with a bandage heals with fewer scars.  ( If  you bandage an injury,  then  it will heal with less scarring.)

2) Complex hypothesis

This one also predicts the relationship between variables but has more than two dependent and independent variables to check for supporting or refusing.

• Overweight people who eat junk food have higher chances of getting excessive cholesterol and heart disease.  (Two independent variables are  extra weight  and  junk food consumption ; two dependent variables are  heart disease  and  high cholesterol level .)
• The higher illiteracy in a society, the higher is poverty and crime rate.  (One independent variable is higher  illiteracy , and two dependent variables are higher  poverty  and higher  crime rate .)

3) Null hypothesis

How to write a null hypothesis? It’s the default position stating there’s no relationship between variables, i.e., there will be no difference in the experiment’s results. 

Scientists use null hypotheses to disapprove or reaffirm given statements.

• A person’s productivity doesn’t suffer from getting six instead of eight hours of sleep.
• All daisies are equal in the number of their petals.
• Sex education in high school doesn’t affect unplanned pregnancy rates.

4) Alternative hypothesis

When searching for information on how to write a hypothesis online, you might see queries like “how to write a null and alternative hypothesis.” That’s because alternative hypothesis statements come in place when someone tries to  disprove  a null hypothesis, so these two go hand in hand.

In other words, an alternative hypothesis  directly contradicts  a null one.

Also, an alternative hypothesis is one you may want to develop when the experiment on your initial statement doesn’t bring any result.

• H0 (a null hypothesis): Light color does not affect plant growth.
• H1 (an alternative hypothesis): Light color affects plant growth.
• H0: Cats have no preference for food based on shape.
• H1: Cats prefer round kibbles to other food shapes.

5) Logical hypothesis

This one is a hypothesis you can verify logically, though there’s little to no substantial evidence for it. Here you use reasoning and logical connections instead of proven facts, statistics, or background research.

Logical hypotheses remain assumptions until you put them to the test and support/refuse them after experiments.

• Dogs won’t survive without water.  (Here, you make an assumption based on the fact humans can’t live without water, so dogs, as mammals, won’t do that, either.)
• Creatures from Mars won’t breathe in the Earth’s atmosphere.  (Here, you assume that they won’t because we humans can’t breathe on Mars.)

6) Empirical hypothesis

In plain English, it’s a currently-tested hypothesis that can yet be changed or adjusted according to the results of experiments. It’s a working hypothesis that’s yet to confirm or refuse:

Empirical hypotheses are those going through tests, trials, or errors via observation and experiments right now and can be changed later around the independent variables. As a rule, it’s the opposite of a logical hypothesis.

• Women taking vitamin E grow hair faster than those taking vitamin K.
• Mushrooms grow faster at 22 degrees Celsius than 27 degrees Celsius.

7) Statistical hypothesis

This one is a hypothesis you can test and verify statistically based on data and quantitative research methods.

How to write a statistical hypothesis?

Statistical hypotheses have quantifiable variables and are usually about the nature of a population. It comes in handy when it’s impossible to test or survey every single person in a group. To write such a hypothesis, you’ll need to state the data about your topic using a portion of people.

• 35% of the poor in the USA are illiterate.
• 60% of people talking on the phone while driving have been in at least one car accident.
• 56% of marriages end in divorce.

How to Write a Hypothesis: 5 Steps

First and foremost, it’s worth mentioning that hypothesis writing is the third step of the scientific method scholars, researchers, and science students use to test theories, answer questions, and solve problems.

The steps are six, and they are as follows:

• Observation:  Decide on an issue to solve or a phenomenon to explain. 
• Question:  Develop a research question you’d like to check.
• Hypothesis (we are here!):  Formulate a hypothesis that answers your question and that you can test.
• Prediction:  Determine the experiment’s outcome based on your hypothesis.
• Test:  Do your experiments to test your prediction.
• Analyze:  Review the results to see if your hypothesis was correct. If it wasn’t, you could revise it by formulating another one and going through the whole process again.

In academic writing, hypotheses come as something relating to thesis statements: It’s a sentence or two summarizing a central claim you’ll discuss and prove in your essay.

It stands to reason that hypothesis writing is more common for STEM disciplines like math, chemistry, biology, physics, or economics. Here’s how to craft it, step by step:

1) Ask a Question

This stage is about choosing an  argumentative topic for your essay . Except as assigned by a teacher or a thesis tutor, you can start with an issue of your interest, so your curiosity and questions on it come naturally.

Why is it the way it is?

Why does it happen the way it goes?

What causes this factor you see around?

Your question needs to be  clear ,  specific , and  manageable  so you can research it, test it, and analyze the results. Also, ensure it’s not too broad so you can focus on its particular aspect to formulate your hypothesis.

For example:   How does eating apples affect human dental health?

2) Conduct Research

Now you’ll need to check and collect some information on your question to understand if it’s possible to formulate a research hypothesis. It’s so-called initial research to find an answer to your question.

This stage is not about proving or disproving your hypothesis. Here you’ll collect facts, theories, past studies, and any other information that will help prove or disprove it so that you can make an apparent assumption: Based on the gathered information, you’ll be able to make a logical guess.

Depending on your question, this initial research can  take some time  from you. You may need to read a few books on the topic, find and compare some scientific materials, etc. Or, it may be enough to perform a quick web search to find the answer.

3) Write a Null Hypothesis

To ease the process of hypothesis writing, start with a null hypothesis. As you already know, it’s the default position stating no relationship between variables. (And that’s why it’s so easy to formulate.)

So, take your initial question and write it as a negative statement. In our example with eating apples and dental health, the null hypothesis would sound like that:

Eating apples do not affect a human’s dental health.

(Which means your teeth condition will be the same, whether you eat apples or not.)

4) Define Variables

And now, for your hypothesis to become testable so you can do experiments, make predictions, and analyze the results, think of dependent and independent variables for it.

As you already know, independent variables are the factors you, as a researcher, can control during experiments to check the hypothesis. 

Example:   Eating one apple a day will positively affect a human’s dental health.

“One apple” is the independent variable, and “dental health” is the dependent variable here.

You’ll come up with variables based on your initial research. With some facts and studies already in place, you can predict how your experiment may go and what its results may be. Use this knowledge to shape variables into a clear and concise hypothesis.

And remember:

The way you’ll frame a hypothesis into one sentence depends on a few factors: the type of your project and the type of hypothesis you want to use. 

Simple hypotheses are most common for student research papers , so we use them as examples here. With that in mind, the final stage of hypothesis writing comes:

5) State It Using an If-Then Format

To formulate a hypothesis the best way possible, try framing it with an “if-then” format. Like this:

If a human eats one apple per day, then he gets healthier teeth.

This format becomes tricky when working with complex hypotheses with multiple variables, but it’s reliable when expressing the cause-and-effect relationship. 

The “if-then” format allows you to refine a hypothesis and ensure its final version:

• is clear, specific, and testable;
• has relevant variables;
• identifies the relationship between variables;
• suggests a predicted result of the experiment.

Another way to check if you’ve shaped a hypothesis properly is using the “PICOT” model, best explained via  visual examples . According to this model, a hypothesis should have five components:

P –  population: the specific group or individual of your research

I –  interest: the primary concern of your study

C –  comparison: the leading alternative group

O –  outcome: the expected result

T – time: the length of your experimen t

Always write a hypothesis in  the present tense  because it refers to research that’s currently being conducted.

What is a Hypothesis in a Research Paper?

A hypothesis in a research paper is a statement demonstrating a prediction you believe may happen based on research, evidence, and experimentation.

Often used and associated with science, hypotheses are assumptions (or guesses) for researchers and scholars to prove or disprove via tests and experiments. And they later write a hypothesis essay to analyze and report the experiments’ results to the scientific community.

When writing a hypothesis for a research paper, you should still describe an experiment to prove or disprove it. However, hypothesis essays don’t necessarily have to be on STEM disciplines and tests taken in a lab:

• You can  write a book critique  and state a hypothesis on its or its author’s impact on literature. 
• Or, your hypothesis essay can be about how demographics change a country’s language.
• Or, you’ll  write an autobiography  with a focus on the hypothesis that one particular event influenced your further deeds. 

In such essays, you won’t spend hours in labs to prove that your hypothesis is true; you’ll do that through research, arguments, data, interviews, or previous studies.

Is a thesis statement a hypothesis?

As we already mentioned, there’s a slight difference between these two. While  thesis statements  in essays are about  summarizing  a central claim you’ll discuss,  hypotheses  are about  predictions  or  assumptions  you’ll prove (or disprove) in the essay body.

You don’t have to prove that your hypothesis is correct. The point is to research, test, and experiment to see if you’re right. Even if your hypothesis appears incorrect in  conclusion , it doesn’t mean the quality of your essay is poor.

How to Write a Hypothesis: Example

And now, let’s go to even more hypothesis examples for you to understand the nature of this writing better.

Here goes another example of a hypothesis:

Frequently Asked Questions

What is a hypothesis in an essay.

A hypothesis in an essay is a statement demonstrating a prediction you believe may happen based on research, evidence, and experimentation. As a rule, it predicts the relationship between a few variables; and you can prove or disprove it by the end of your tests and experiments on it.

How long is a hypothesis?

A hypothesis is one-sentence long. It should be clear, direct, and testable through experimentation, predicting a possible outcome.

How to write a hypothesis statement?

First of all, you need to state a problem you’re trying to solve, do some initial research on it to learn the background and predict an outcome, and then think of both dependent and independent variables for your hypothesis. For that, research or brainstorm ideas for your stated problem’s solution. Finally, write your hypothesis as an “if-then” statement, using your variables.

How to write a null hypothesis?

A null hypothesis is the default position stating no relationship between variables. To write it, you need to assume an experiment has no effect regardless of variables; use denying. 

For example, you want to learn whether teens are better at math than adults. In this case, your null hypothesis will be, “ Age does not affect math ability.”

How to write an alternative hypothesis?

An alternative hypothesis directly contradicts   a null one, trying to disprove it. To write it, you need to assume there’s enough evidence to reject the null hypothesis; but never state your claim is already proven true or false.

In contrast with a null hypothesis, typically marked as H0, an alternative one gets an H1 mark. For example:

H0: If I put Mentos into a Coke bottle, there will be no reaction.

H1: If I put Mentos into a Coke bottle, there will be a big explosion.

How to write a simple hypothesis?

A simple hypothesis is the most common one to use in college papers. It predicts the direct relationship between two variables — one dependent and one independent, — so write a simple hypothesis with an “if-then” format.

For example: 

If a postpartum woman has low hemoglobin, then she gets higher risk of infection.

A statistical hypothesis claims the value of a single population characteristic or relationship between several population characteristics. To write it, you first need to specify null and alternative hypotheses, set the significance level, calculate the statistics, and draw a conclusion. Ensure that your variables are quantifiable. For example: 

A population mean is equal to 10.

How to write a hypothesis for a lab report?

To write a hypothesis for a lab report, you should state the issue, predict its outcome based on tests and experiments, define the variables, and formulate a hypothesis as an if-then statement. For example:

If one puts Mentos in a bottle with Coke, there will be an explosion.

How to write a hypothesis for a research paper?

• Decide on a question/problem you want to check/solve.
• Conduct initial research to collect as much background information and observation about your topic as you can.
• Evaluate this information to assume possible causes and possible explanations.
• Define variables you’ll use to confirm or disprove your hypothesis through experimentation.
• Write down a one-sentence hypothesis using the present tense.

Now that you know how to write a hypothesis, it’s high time to give it a try:

• Address your curiosity.
• Ask questions.
• Conduct some initial research.
• Come up with a type of hypothesis that fits your expectations most.

Think of variables for your hypothesis, and ensure it’s clear, concise, and measurable (testable). Then write it in the present tense — and you’ve got it!

Any questions left? Don’t hesitate to write in the comments (yes, we read them and reply!) or ask  Bid4Papers writers  directly!

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