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How to Write a Hypothesis: Step-By-Step Guide

A hypothesis is a testable statement that guides scientific research. Want to know how to write a hypothesis for your research paper? This guide will show you the key steps involved, including defining your variables and phrasing your hypothesis correctly.

Key Takeaways

• A hypothesis is a testable statement proposed for investigation, grounded in existing knowledge, essential for guiding scientific research.
• Understanding different types of hypotheses, including simple, complex, null, and alternative, is crucial for selecting appropriate research approaches.
• Crafting a strong hypothesis involves a systematic process including defining variables, phrasing it as an if-then statement, and ensuring it is clear, specific, and testable.

Understanding a Hypothesis

An empirical hypothesis is not just a simple guess. It represents a preliminary concept that stands to be scrutinized through Research and experimentation. A well-constructed hypothesis is a fundamental component of the scientific method, guiding experiments and leading to conclusions. Within the realm of science, such hypotheses are crafted after an extensive examination of current knowledge, ensuring their foundation on already established evidence prior to beginning any new inquiry.

Essentially, a hypothesis in the scientific community must present itself as something capable of being tested, this characteristic distinguishes it from mere speculation by allowing its potential verification or falsification through methodical scrutiny. Hypotheses serve as crucial instruments within scientific studies, directing these investigations toward particular queries and forming the backbone upon which all experiments rest in their pursuit for advancements in comprehension.

When formulating a hypothesis for testing within research activities, one should employ language that remains neutral and detached from subjective bias thereby bolstering the legitimacy of outcomes produced during the study. This precision fosters greater confidence in results obtained under rigorous evaluation standards among peers.

Characteristics of a Good Hypothesis

A good hypothesis is the cornerstone of any successful scientific research. It should be clear, concise, and testable, providing a solid foundation for your investigation. Here are some key characteristics that define a good hypothesis:

• Clarity : A good hypothesis should be easy to understand and clearly state the expected outcome of the research. For example , “Increased exposure to sunlight will result in taller plant growth” is a clear and straightforward hypothesis.
• Conciseness : Avoid unnecessary complexity or jargon. A concise hypothesis is brief and to the point, making it easier to test and analyze. For instance, “Exercise improves mental health” is concise and direct.
• Testability : A good hypothesis must be testable and falsifiable, meaning it can be proven or disproven through scientific research methods. For example, “Consuming vitamin C reduces the duration of the common cold” is a testable hypothesis.
• Relevance : Ensure your hypothesis is relevant to the research question or problem and aligned with your research objectives. For example, if your research question is about the impact of diet on health, a relevant hypothesis could be “A high-fiber diet reduces the risk of heart disease.”
• Specificity : A good hypothesis should be specific and focused on a particular aspect of the research question. For example, “Daily meditation reduces stress levels in college students” is specific and targeted.
• Measurability : Your hypothesis should be measurable, meaning it can be quantified or observed. For example, “Regular physical activity lowers blood pressure” is a measurable hypothesis.

By ensuring your hypothesis possesses these characteristics, you set a strong foundation for your scientific research, guiding your investigation towards meaningful and reliable results.

Types of Hypotheses

Scientific research incorporates a range of research hypotheses, which are crucial for proposing relationships between different variables and steering the direction of the investigation. These seven unique forms of hypotheses cater to diverse needs within the realm of scientific inquiry.

Comprehending these various types is essential in selecting an appropriate method for conducting research. To delve into details, we have simple, complex, null and alternative hypotheses. Each brings its distinct features and practical implications to the table. It underscores why recognizing how they diverge and what purposes they serve is fundamental in any scientific study.

Simple Hypothesis

A basic hypothesis suggests a fundamental relationship between two elements: the independent and dependent variable. Take, for example, a hypothesis that says, “The taller growth of plants (dependent variable) is due to increased exposure to sunlight (independent variable).” Such hypotheses are clear-cut and easily testable as they concentrate on one direct cause-and-effect link.

These types of straightforward hypotheses are very beneficial in scientific experiments because they permit the isolation of variables for precise outcome measurement. Their simplicity lends itself well to being an essential component in conducting scientific research, thanks to their unambiguous nature and targeted focus on specific relationships.

Complex Hypothesis

Alternatively, a complex hypothesis proposes an interconnection amongst several variables. It builds on the concept of numerous variable interactions within research parameters. Take for instance a causal hypothesis which asserts that sustained alcohol consumption (the independent variable) leads to liver impairment (the dependent variable), with additional influences like use duration and general health results impacting this relationship.

Involving various factors, complex hypotheses reveal the nuanced interaction of elements that affect results. Although they provide extensive insight into studied phenomena, such hypotheses necessitate advanced research frameworks and analysis techniques to be understood properly.

Null Hypothesis

In the realm of hypothesis testing, the null hypothesis (H0) serves as a fundamental presumption suggesting that there exists no association between the variables under investigation. It posits that variations within the dependent variable are attributed to random chance and not an influential relationship. Take for instance a null hypothesis which could propose “There is no impact of sleep duration on productivity levels.”

The significance of the null hypothesis lies in its role as a reference point which researchers strive to refute during their investigations. Upon uncovering statistical evidence indicative of a substantial linkage, it becomes necessary to discard the null hypothesis. The act of rejecting this foundational assumption is critical for affirming research findings and assessing their importance with respect to outcomes observed.

Alternative Hypothesis

The alternative hypothesis, often represented by H1 or Ha, contradicts the null hypothesis and proposes a meaningful link between variables under examination. For example, where the null hypothesis asserts that a particular medication is ineffective, the alternative might posit that “Compared to placebo treatment, the new drug yields beneficial effects.”

By claiming outcomes are non-random and carry weight, the alternative hypothesis bolsters theoretical assertions. Its testable prediction propels scientific investigation forward as it aims either to corroborate or debunk what’s posited by the null hypothesis.

Consider an assertive statement like “Productivity is influenced by sleep duration” which serves as a crisp articulation of an alternative hypothesis.

Steps to Write a Hypothesis

Crafting a hypothesis is a methodical process that begins with curiosity and culminates in a testable prediction. Writing a hypothesis involves following structured steps to ensure clarity, focus, and researchability. Steps include asking a research question, conducting preliminary research, defining variables, and phrasing the hypothesis as an if-then statement.

Each step is critical in formulating a strong hypothesis to guide research and lead to meaningful discoveries.

Ask a Research Question

A well-defined research question forms the cornerstone of a strong hypothesis, guiding your investigation towards a significant and targeted exploration. By rooting this question in observations and existing studies, it becomes pertinent and ripe for research. For example, noting that certain snacks are more popular could prompt the inquiry: “Does providing healthy snack options in an office setting enhance employee productivity?”.

Such a thoughtfully constructed question lays the groundwork for your research hypothesis, steering your scholarly work to be concentrated and purposeful.

Conduct Preliminary Research

Begin your research endeavor by conducting preliminary investigations into established theories, past studies, and available data. This initial stage is crucial as it equips you with a comprehensive background to craft an informed hypothesis while pinpointing any existing voids in current knowledge. Understanding the concept of a statistical hypothesis can also be beneficial, as it involves drawing conclusions about a population based on a sample and applying statistical evidence.

By reviewing literature and examining previously published research papers, one can discern the various variables of interest and their interconnections. Should the findings from these early inquiries refute your original hypothesis, adjust it accordingly so that it resonates with already recognized evidence.

Define Your Variables

A well-formed hypothesis should unambiguously identify the independent and dependent variables involved. In an investigation exploring how plant growth is affected by sunlight, for instance, plant height represents the dependent variable, while the quantity of sunlight exposure constitutes the independent variable.

It is essential to explicitly state all the variables included in a study so that the hypothesis can be tested with accuracy and specificity. Defining these variables distinctly facilitates a targeted and quantifiable examination.

Phrase as an If-Then Statement

A good hypothesis is typically structured in the form of if-then statements, allowing for a clear demonstration of the anticipated link between different variables. Take, for example, stating that administering drug X could result in reduced fatigue among patients. This outcome would be especially advantageous to individuals receiving cancer therapy. The structure aids in explicitly defining the cause-and-effect dynamic.

In order to craft a strong hypothesis, it should be capable of being tested and grounded on existing knowledge or theoretical frameworks. It should also be framed as a statement that can potentially be refuted by experimental data, which qualifies it as a solidly formulated hypothesis.

Collect Data to Support Your Hypothesis

Once you have formulated a hypothesis, the next crucial step is to collect data to support or refute it. This involves designing and conducting experiments or studies that test the hypothesis, and collecting and analyzing data to determine whether the hypothesis holds true.

Here are the key steps in collecting data to support your hypothesis:

• Designing an Experiment or Study : Start by identifying your research question or problem. Design a study or experiment that specifically tests your hypothesis. For example, if your hypothesis is “Daily exercise improves cognitive function,” design an experiment that measures cognitive function in individuals who exercise daily versus those who do not.
• Collecting Data : Gather data through various methods such as experiments, surveys, observations, or other techniques. Ensure your data collection methods are reliable and valid. For instance, use standardized tests to measure cognitive function in your exercise study.
• Analyzing Data : Use statistical methods or other techniques to analyze the data. This step involves determining whether the data supports or refutes your hypothesis. For example, use statistical tests to compare cognitive function scores between the exercise and non-exercise groups .
• Interpreting Results : Interpret the results of your data analysis to determine whether your hypothesis is supported. For instance, if the exercise group shows significantly higher cognitive function scores, your hypothesis is supported. If not, you may need to refine your hypothesis or explore other variables.

By following these steps, you can systematically collect and analyze data to support or refute your hypothesis, ensuring your research is grounded in empirical evidence.

Refining Your Hypothesis

To ensure your hypothesis is precise, comprehensible, verifiable, straightforward, and pertinent, you must refine it meticulously. Creating a compelling hypothesis involves careful consideration of its transparency, purposeful direction and the potential results. This requires unmistakably delineating the subject matter and central point of your experiment.

Your hypothesis should undergo stringent examination to remove any uncertainties and define parameters that guarantee both ethical integrity and scientific credibility. An effective hypothesis not only questions prevailing assumptions, but also maintains an ethically responsible framework.

Testing Your Hypothesis

Having a robust research methodology is essential for efficiently evaluating your hypothesis. It is important to ensure that the integrity and validity of the research are upheld through adherence to ethical standards. The data gathered ought to be both representative and tailored specifically towards validating or invalidating the hypothesis.

In order to ascertain whether there’s any significant difference, statistical analyses measure variations both within and across groups. Frequently, the decision on whether to discard the null hypothesis hinges on establishing a p-value cut-off point, which conventionally stands at 0.05.

Tips for Writing a Research Hypothesis

Writing a research hypothesis can be a challenging task, but with the right approach, you can craft a strong and testable hypothesis. Here are some tips to help you write a research hypothesis:

• Start with a Research Question : A good hypothesis starts with a clear and focused research question. For example, “Does regular exercise improve mental health?” can lead to a hypothesis like “Regular exercise reduces symptoms of depression.”
• Conduct Preliminary Research : Conducting preliminary research helps you identify a knowledge gap in your field and develop a hypothesis that is relevant and testable. Review existing literature and studies to inform your hypothesis.
• Use Clear and Concise Language : A good hypothesis should be easy to understand and use clear and concise language. Avoid jargon and complex terms. For example, “Increased screen time negatively impacts sleep quality” is clear and straightforward.
• Avoid Ambiguity and Vagueness : Ensure your hypothesis is free from ambiguity and vagueness. Clearly state the expected outcome of the research. For example, “Consuming caffeine before bedtime reduces sleep duration” is specific and unambiguous.
• Make Sure It Is Testable : A good hypothesis should be testable and falsifiable, meaning it can be proven or disproven through scientific research methods. For example, “A high-protein diet increases muscle mass” is a testable hypothesis.
• Use Existing Knowledge and Research : Base your hypothesis on existing knowledge and research. Align it with your research objectives and ensure it is grounded in established theories or findings.

Common mistakes to avoid when writing a research hypothesis include:

• Making It Too Broad or Too Narrow : A good hypothesis should be specific and focused on a particular aspect of the research question. Avoid overly broad or narrow hypotheses.
• Making It Too Vague or Ambiguous : Ensure your hypothesis is clear and concise, avoiding ambiguity and vagueness.
• Failing to Make It Testable : A good hypothesis should be testable and falsifiable. Ensure it can be proven or disproven through scientific research methods.
• Failing to Use Existing Knowledge and Research : Base your hypothesis on existing knowledge and research. Align it with your research objectives and ensure it is grounded in established theories or findings.

By following these tips and avoiding common mistakes, you can write a strong and testable research hypothesis that will guide your scientific investigation towards meaningful and reliable results.

Examples of Good and Bad Hypotheses

A well-constructed hypothesis is distinct, precise, and capable of being empirically verified. To be considered a good hypothesis, it must offer measurable and examinable criteria through experimental means. Take the claim “Working from home boosts job satisfaction” as an example. This posits a testable outcome related to work environments.

On the other hand, a subpar hypothesis such as “Garlic repels vampires” falls short because it hinges on fantastical elements that cannot be substantiated or refuted in reality. The ability to distinguish between strong and weak hypotheses plays an essential role in conducting successful research.

Importance of a Testable Hypothesis

A hypothesis that can be subjected to testing forms the basis of a scientific experiment, outlining anticipated results. For a hypothesis to qualify as testable, it must possess key attributes such as being able to be falsified and verifiable or disprovable via experimental means. It serves as an essential platform for conducting fresh research with the potential to confirm or debunk it.

Crafting a robust testable hypothesis yields clear forecasts derived from previous studies. Should both the predictions and outcomes stemming from a hypothesis lack this critical aspect of testability, they will remain ambiguous, rendering the associated experiment ineffective in conclusively proving or negating anything of substance.

In summary, crafting a strong hypothesis constitutes an essential ability within the realm of scientific research. Grasping the various forms of hypotheses and mastering the process for their formulation and refinement are critical to establishing your research as solid and significant. It is crucial to underscore that having a testable hypothesis serves as the bedrock for successful scientific investigation.

Frequently Asked Questions

How can you formulate a hypothesis.

To formulate a hypothesis, first state the question your experiment aims to answer and identify the independent and dependent variables.

Then create an “If, Then” statement that succinctly defines the relationship between these variables.

What is a hypothesis in scientific research?

In the research process, a hypothesis acts as a tentative concept that is put forward for additional scrutiny and examination, establishing the bedrock upon which scientific experiments are built. It steers the course of research by forecasting possible results.

What are the different types of hypotheses?

Hypotheses can be classified into simple, complex, null, and alternative types, each type fulfilling distinct roles in scientific research.

Understanding these differences is crucial for effective hypothesis formulation.

How do I write a hypothesis?

To write a hypothesis, start by formulating a research question and conducting preliminary research.

Then define your variables and express your hypothesis in the form of an if-then statement.

Why is a testable hypothesis important?

Having a testable hypothesis is vital because it provides a definitive structure for conducting research, allowing for particular predictions that experimentation can either verify or refute.

Such an element significantly improves the process of scientific investigation.

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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 .

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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? Types and Examples 

All research studies involve the use of the scientific method, which is a mathematical and experimental technique used to conduct experiments by developing and testing a hypothesis or a prediction about an outcome. Simply put, a hypothesis is a suggested solution to a problem. It includes elements that are expressed in terms of relationships with each other to explain a condition or an assumption that hasn’t been verified using facts. 1 The typical steps in a scientific method include developing such a hypothesis, testing it through various methods, and then modifying it based on the outcomes of the experiments.  

A research hypothesis can be defined as a specific, testable prediction about the anticipated results of a study. 2 Hypotheses help guide the research process and supplement the aim of the study. After several rounds of testing, hypotheses can help develop scientific theories. 3 Hypotheses are often written as if-then statements. 

Here are two hypothesis examples: 

Dandelions growing in nitrogen-rich soils for two weeks develop larger leaves than those in nitrogen-poor soils because nitrogen stimulates vegetative growth. 4  

If a company offers flexible work hours, then their employees will be happier at work. 5  

Table of Contents

• What is a hypothesis? 
• Types of hypotheses 
• Characteristics of a hypothesis 
• Functions of a hypothesis 
• How to write a hypothesis 
• Hypothesis examples 
• Frequently asked questions 

What is a hypothesis?

A hypothesis expresses an expected relationship between variables in a study and is developed before conducting any research. Hypotheses are not opinions but rather are expected relationships based on facts and observations. They help support scientific research and expand existing knowledge. An incorrectly formulated hypothesis can affect the entire experiment leading to errors in the results so it’s important to know how to formulate a hypothesis and develop it carefully.

A few sources of a hypothesis include observations from prior studies, current research and experiences, competitors, scientific theories, and general conditions that can influence people. Figure 1 depicts the different steps in a research design and shows where exactly in the process a hypothesis is developed. 4  

There are seven different types of hypotheses—simple, complex, directional, nondirectional, associative and causal, null, and alternative. 

Types of hypotheses

The seven types of hypotheses are listed below: 5 , 6,7  

• Simple : Predicts the relationship between a single dependent variable and a single independent variable. 

Example: Exercising in the morning every day will increase your productivity.  

• Complex : Predicts the relationship between two or more variables. 

Example: Spending three hours or more on social media daily will negatively affect children’s mental health and productivity, more than that of adults.  

• Directional : Specifies the expected direction to be followed and uses terms like increase, decrease, positive, negative, more, or less. 

Example: The inclusion of intervention X decreases infant mortality compared to the original treatment.  

• Non-directional : Does not predict the exact direction, nature, or magnitude of the relationship between two variables but rather states the existence of a relationship. This hypothesis may be used when there is no underlying theory or if findings contradict prior research. 

Example: Cats and dogs differ in the amount of affection they express.  

• Associative and causal : An associative hypothesis suggests an interdependency between variables, that is, how a change in one variable changes the other.  

Example: There is a positive association between physical activity levels and overall health.  

A causal hypothesis, on the other hand, expresses a cause-and-effect association between variables. 

Example: Long-term alcohol use causes liver damage.  

• Null : Claims that the original hypothesis is false by showing that there is no relationship between the variables. 

Example: Sleep duration does not have any effect on productivity.  

• Alternative : States the opposite of the null hypothesis, that is, a relationship exists between two variables. 

Example: Sleep duration affects productivity.  

Characteristics of a hypothesis

So, what makes a good hypothesis? Here are some important characteristics of a hypothesis. 8,9  

• Testable : You must be able to test the hypothesis using scientific methods to either accept or reject the prediction. 
• Falsifiable : It should be possible to collect data that reject rather than support the hypothesis. 
• Logical : Hypotheses shouldn’t be a random guess but rather should be based on previous theories, observations, prior research, and logical reasoning. 
• Positive : The hypothesis statement about the existence of an association should be positive, that is, it should not suggest that an association does not exist. Therefore, the language used and knowing how to phrase a hypothesis is very important. 
• Clear and accurate : The language used should be easily comprehensible and use correct terminology. 
• Relevant : The hypothesis should be relevant and specific to the research question. 
• Structure : Should include all the elements that make a good hypothesis: variables, relationship, and outcome. 

Functions of a hypothesis

The following list mentions some important functions of a hypothesis: 1  

• Maintains the direction and progress of the research. 
• Expresses the important assumptions underlying the proposition in a single statement. 
• Establishes a suitable context for researchers to begin their investigation and for readers who are referring to the final report. 
• Provides an explanation for the occurrence of a specific phenomenon. 
• Ensures selection of appropriate and accurate facts necessary and relevant to the research subject. 

To summarize, a hypothesis provides the conceptual elements that complete the known data, conceptual relationships that systematize unordered elements, and conceptual meanings and interpretations that explain the unknown phenomena. 1  

How to write a hypothesis

Listed below are the main steps explaining how to write a hypothesis. 2,4,5  

• Make an observation and identify variables : Observe the subject in question and try to recognize a pattern or a relationship between the variables involved. This step provides essential background information to begin your research.  

For example, if you notice that an office’s vending machine frequently runs out of a specific snack, you may predict that more people in the office choose that snack over another. 

• Identify the main research question : After identifying a subject and recognizing a pattern, the next step is to ask a question that your hypothesis will answer.  

For example, after observing employees’ break times at work, you could ask “why do more employees take breaks in the morning rather than in the afternoon?” 

• Conduct some preliminary research to ensure originality and novelty : Your initial answer, which is your hypothesis, to the question is based on some pre-existing information about the subject. However, to ensure that your hypothesis has not been asked before or that it has been asked but rejected by other researchers you would need to gather additional information.  

For example, based on your observations you might state a hypothesis that employees work more efficiently when the air conditioning in the office is set at a lower temperature. However, during your preliminary research you find that this hypothesis was proven incorrect by a prior study. 

• Develop a general statement : After your preliminary research has confirmed the originality of your proposed answer, draft a general statement that includes all variables, subjects, and predicted outcome. The statement could be if/then or declarative.  
• Finalize the hypothesis statement : Use the PICOT model, which clarifies how to word a hypothesis effectively, when finalizing the statement. This model lists the important components required to write a hypothesis. 

P opulation: The specific group or individual who is the main subject of the research 

I nterest: The main concern of the study/research question 

C omparison: The main alternative group 

O utcome: The expected results  

T ime: Duration of the experiment 

Once you’ve finalized your hypothesis statement you would need to conduct experiments to test whether the hypothesis is true or false. 

Hypothesis examples

The following table provides examples of different types of hypotheses. 10 ,11  

Key takeaways  

Here’s a summary of all the key points discussed in this article about how to write a hypothesis. 

• A hypothesis is an assumption about an association between variables made based on limited evidence, which should be tested. 
• A hypothesis has four parts—the research question, independent variable, dependent variable, and the proposed relationship between the variables.   
• The statement should be clear, concise, testable, logical, and falsifiable. 
• There are seven types of hypotheses—simple, complex, directional, non-directional, associative and causal, null, and alternative. 
• A hypothesis provides a focus and direction for the research to progress. 
• A hypothesis plays an important role in the scientific method by helping to create an appropriate experimental design. 

Frequently asked questions

Hypotheses and research questions have different objectives and structure. The following table lists some major differences between the two. 9  

Here are a few examples to differentiate between a research question and hypothesis. 

Yes, here’s a simple checklist to help you gauge the effectiveness of your hypothesis. 9   1. When writing a hypothesis statement, check if it:  2. Predicts the relationship between the stated variables and the expected outcome.  3. Uses simple and concise language and is not wordy.  4. Does not assume readers’ knowledge about the subject.  5. Has observable, falsifiable, and testable results. 

As mentioned earlier in this article, a hypothesis is an assumption or prediction about an association between variables based on observations and simple evidence. These statements are usually generic. Research objectives, on the other hand, are more specific and dictated by hypotheses. The same hypothesis can be tested using different methods and the research objectives could be different in each case.     For example, Louis Pasteur observed that food lasts longer at higher altitudes, reasoned that it could be because the air at higher altitudes is cleaner (with fewer or no germs), and tested the hypothesis by exposing food to air cleaned in the laboratory. 12 Thus, a hypothesis is predictive—if the reasoning is correct, X will lead to Y—and research objectives are developed to test these predictions. 

Null hypothesis testing is a method to decide between two assumptions or predictions between variables (null and alternative hypotheses) in a statistical relationship in a sample. The null hypothesis, denoted as H 0 , claims that no relationship exists between variables in a population and any relationship in the sample reflects a sampling error or occurrence by chance. The alternative hypothesis, denoted as H 1 , claims that there is a relationship in the population. In every study, researchers need to decide whether the relationship in a sample occurred by chance or reflects a relationship in the population. This is done by hypothesis testing using the following steps: 13   1. Assume that the null hypothesis is true.  2. Determine how likely the sample relationship would be if the null hypothesis were true. This probability is called the p value.  3. If the sample relationship would be extremely unlikely, reject the null hypothesis and accept the alternative hypothesis. If the relationship would not be unlikely, accept the null hypothesis. 

To summarize, researchers should know how to write a good hypothesis to ensure that their research progresses in the required direction. A hypothesis is a testable prediction about any behavior or relationship between variables, usually based on facts and observation, and states an expected outcome.  

We hope this article has provided you with essential insight into the different types of hypotheses and their functions so that you can use them appropriately in your next research project. 

References  

• Dalen, DVV. The function of hypotheses in research. Proquest website. Accessed April 8, 2024. https://www.proquest.com/docview/1437933010?pq-origsite=gscholar&fromopenview=true&sourcetype=Scholarly%20Journals&imgSeq=1  
• McLeod S. Research hypothesis in psychology: Types & examples. SimplyPsychology website. Updated December 13, 2023. Accessed April 9, 2024. https://www.simplypsychology.org/what-is-a-hypotheses.html  
• Scientific method. Britannica website. Updated March 14, 2024. Accessed April 9, 2024. https://www.britannica.com/science/scientific-method  
• The hypothesis in science writing. Accessed April 10, 2024. https://berks.psu.edu/sites/berks/files/campus/HypothesisHandout_Final.pdf  
• How to develop a hypothesis (with elements, types, and examples). Indeed.com website. Updated February 3, 2023. Accessed April 10, 2024. https://www.indeed.com/career-advice/career-development/how-to-write-a-hypothesis  
• Types of research hypotheses. Excelsior online writing lab. Accessed April 11, 2024. https://owl.excelsior.edu/research/research-hypotheses/types-of-research-hypotheses/  
• What is a research hypothesis: how to write it, types, and examples. Researcher.life website. Published February 8, 2023. Accessed April 11, 2024. https://researcher.life/blog/article/how-to-write-a-research-hypothesis-definition-types-examples/  
• Developing a hypothesis. Pressbooks website. Accessed April 12, 2024. https://opentext.wsu.edu/carriecuttler/chapter/developing-a-hypothesis/  
• What is and how to write a good hypothesis in research. Elsevier author services website. Accessed April 12, 2024. https://scientific-publishing.webshop.elsevier.com/manuscript-preparation/what-how-write-good-hypothesis-research/  
• How to write a great hypothesis. Verywellmind website. Updated March 12, 2023. Accessed April 13, 2024. https://www.verywellmind.com/what-is-a-hypothesis-2795239  
• 15 Hypothesis examples. Helpfulprofessor.com Published September 8, 2023. Accessed March 14, 2024. https://helpfulprofessor.com/hypothesis-examples/ 
• Editage insights. What is the interconnectivity between research objectives and hypothesis? Published February 24, 2021. Accessed April 13, 2024. https://www.editage.com/insights/what-is-the-interconnectivity-between-research-objectives-and-hypothesis  
• Understanding null hypothesis testing. BCCampus open publishing. Accessed April 16, 2024. https://opentextbc.ca/researchmethods/chapter/understanding-null-hypothesis-testing/#:~:text=In%20null%20hypothesis%20testing%2C%20this,said%20to%20be%20statistically%20significant  

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