Learn how to write a hypothesis in eight easy steps.
In academic writing, you often need to write a hypothesis. A hypothesis can serve as a thesis statement in a paper and as a guide when starting some research or experimentation.
In science, a hypothesis is sometimes called an “educated guess.” It is an essential part of the scientific method. Scientists will do initial testing and research when they discover a potential problem. This will lead them to a hypothesis, a proposed solution to the problem, or a relationship between the stated variables in their research.
A strong hypothesis will be clear and testable. It will also have some predictions. It typically will have relevant variables that work with one another to prove or disprove the idea the researcher has in mind. It will also define the variables clearly so that anyone reading the hypothesis knows precisely what those variables are.
Learning how to write a hypothesis is not always easy, but it is a valuable skill, particularly if you are entering a field that involves quite a bit of research. Here is a step-by-step guide to help you know how to write this critical statement.
- Pen or pencil
- Research materials
Step 1: Know the Types of Hypotheses
Before writing your hypothesis, you need to know what kind of hypothesis you’re writing.
Hypotheses come in six basic forms:
- Simple research hypothesis: A simple hypothesis shows one dependent variable and one independent variable. You may say, “If you eat junk food, you will gain weight.”
- Complex research hypothesis: A complex hypothesis has two or more dependent and independent variables. You might say, “If you eat more whole grains and vegetables, you will lose weight and have healthier skin.
- Directional hypothesis: This hypothesis shows that the writer or researcher already knows where the outcome will go. You might say, “Children who ate more fruits and vegetables in preschool had higher IQ levels than those who struggled with hunger over the past five-year period.”
- Non-directional hypothesis: This hypothesis shows a relationship without a theory as to how that relationship will show up. You might say, “Nutrition directly affects the educational outcome of elementary students.”
- Null Hypothesis: This hypothesis is a statement contrary to the research hypothesis. A null hypothesis negates any relationship between the variables. For example, if you said, “Nutrition has no relationship to hyperactivity,” you would be stating a null hypothesis.
- Associative and Causal Hypothesis: This final type is a pair of types. In an associative hypothesis, a change in one variable will cause a change in the other. In the causal hypothesis, the relationship shown is a cause-and-effect relationship between two variables.
You may also run into a working hypothesis in your research. A working hypothesis is one that people in your profession tend to accept, but that still requires additional research to be fully proven. The working hypothesis is sometimes called an empirical hypothesis. However, once enough data support the hypothesis, it becomes a theory.
Step 2: Create a Research Question
Before someone can start researching and creating a hypothesis, they must identify a problem to be solved. Once the problem is identified, you can move to researching and writing a hypothesis. The problem will usually lead to the research question being the question you hope to answer in your experiment or study. Therefore, your question needs to be specific. It also needs to be focused. Finally, it must fit within the guidelines and structure of your project or experiment. For example, you may wonder about sun exposure’s mental health benefits. You could ask:
- Does sun exposure have an impact on someone’s mood?
This question will guide you to the next step.
Step 3: Conduct Research
Now you need to do some preliminary research. Because a hypothesis is an educated guess, you must do some education to make that guess. In your research, hone in on your variables. The variables are the things that change in the experiment. You will have two types:
- Independent variables: These are the variables that the researcher has control over or can change.
- Dependent variables: These are the variables that may or may not change based on the independent variables, and these are what the researcher will measure and observe.
In the example about sun exposure, the amount of sun exposure would be the independent variable. The resulting mood would be the dependent variable. Here is another hypothesis example:
- If I floss and brush my teeth daily, I will not develop cavities.
Here the independent variable is your oral hygiene. The dependent variable is the health of your teeth or your lack of cavities.
Step 4: Discover the Relationship
As you research your topic, find the relationship you wish to study. The above examples are relatively straightforward, but perhaps you will discover a relationship between watering plants and overall plant growth if your research topic is a botany topic. Then, you could use that relationship to create a hypothesis statement:
- Since adding 10 ml of water every other day caused plant growth, adding 20 ml would cause more plant growth.
While your hypothesis may or may not prove true, this shows the relationship between water and growth. You would then perform a scientific experiment to determine if the relationship held for a larger water amount.
Step 5: Write Your Hypothesis
Now that you have researched, outlined your different variables, and determined the relationship, you are ready to write a hypothesis. Your hypothesis is a basic answer to your research question at this stage. So, if your research question was one about the sun and a person’s mood, you could write:
- Spending time in the sun will increase someone’s feelings of happiness while decreasing problems with depression.
Step 6: Revise Your Hypothesis
Next, you will need to refine your hypothesis to make sure it is a strong hypothesis. A strong hypothesis is:
- A logical hypothesis based on research
- A testable hypothesis
- Clearly defined with clear variables
If you feel that your hypothesis is not logical or testable, is too vague, or does not have clear variables, take some time to refine it.
Step 7: Create Three Forms
Your hypothesis can be written in three ways. First, a simple hypothesis is usually written in an “if/then” format, such as:
- If you spend more time in the sun, you will have fewer problems with depression and experience more happiness.
It would be best if you rephrased the hypothesis for academic writing and research to show a predicted relationship. For example, this might look like this:
Finally, you can use your hypothesis to compare two groups like this:
- People who spend more time in the sun have happier moods with less risk of depression compared to those that do not spend time in the sun.
Decide which format fits the purpose of your hypothesis statement.
Step 8: Write a Null and Alternative Hypothesis
If you are doing statistical hypothesis testing as part of your research, your hypothesis needs a hull hypothesis. The null hypothesis shows that there is no connection between the variables.
The null hypothesis for the sun example would read:
- Spending time in the sun has no impact on mood.
Then, for this type of research, you will write an alternative hypothesis, which would read:
- Spending time in the sun has a positive impact on mood.
Not all research projects require this pair of hypotheses, but knowing how to write them helps if yours does.
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