If you’re new to the sciences, you’re going to need to learn how to write a hypothesis pretty early in your academic career. Writing and creating a hypothesis is an integral component for almost every scientific field, and even some non-science fields.
Science is all about learning more truths about the world around us. Being able to formulate a hypothesis and put it to the test in an experiment is a key component to creating new theories, laws, and technologies. Many of the technologies and innovations we use today have started with someone who came up with a hypothesis, from vaccinations to computers and smartphones.
That being said, when you’re starting out as a science student, a lot of this can be overwhelming, but that’s why we’re here. In this article, we’re going to break down everything you need to know to learn how to write a hypothesis for your science experiment, study, report, or anything else you may need to do.
Young male scientist making an observation in a lab
The Scientific Method
Developing a hypothesis is actually the third step in the scientific method, something you’re going to become very familiar with when you enter any science-related field of study, from geology to biology, nursing, and psychology.
The scientific method is a process or series of steps that researchers take to answer questions, solve problems, and test theories about the world. It’s also the process scientists use in order to determine and create the laws of science.
Of course, experimenting and testing have been part of scientific discovery since the ancient civilizations. There has even been evidence found on ancient Egyptian papyrus scrolls outlining a method for diagnosing a medical patient that resembles an early version of the scientific method. This process has been used in some form by some of the greatest discoverers and thinkers in history, like Aristotle, Francis Bacon, Isaac Newton, and Galileo Galilei.
Over time, the scientific method was formed and developed further into viable, standardized steps that are now taught as part of the universally accepted science curriculum as early as high school.
There are six steps to the scientific method:
● 1. Observation: Make an observation about something, such as an issue to solve or a phenomenon that occurs.
● 2. Question: Develop a research question related to your observation.
● 3. Hypothesis: Formulate a hypothesis you can test.
● 4. Prediction: Determine what you think the outcome of the experiment will be.
● 5. Test: Perform your experiment.
● 6. Analyze: Review the data and results and create a conclusion. Was your prediction correct?
Female teacher writing a scientific equation using data on the blackboard
What is a Hypothesis?
Like most new concepts and terms, the first step to learning how to write a hypothesis is learning what a hypothesis actually is. Essentially, a hypothesis is an assumption or explanation for something based on limited background research or untested knowledge. In other words, it’s an educated guess.
You’re taking what you know already about a conclusion or observation and putting it into a statement that can be tested to prove that observation is correct. Your knowledge or background research on the subject doesn’t have to be extensive, but it should be enough to understand that something is likely to happen. It could also be rooted in common sense.
For example, let’s say you’ve been indulging in a lot of holiday treats lately and you notice that you’ve been having weird dreams at night. When you Google it, you find this academic study that indicates there’s a link between eating sugar at night and bizarre dream function. When you look back at your patterns from the last few weeks, you realize you’ve been eating those holiday goodies before bed. Therefore, based on this background research and your own lifestyle patterns, your hypothesis would be that eating sugar before bed has led you to experience strange dreams.
If you wanted to take this theory one step further, you could follow the scientific method and devise an easy experiment to confirm whether your hypothesis is true or not.
Conditional Statements: The If, Then This Rule
The general rule of thumb for a hypothesis is that you should follow the if, then this rule, also known as a conditional statement. It boils down to this: if a specific action is taken, then this other outcome will likely occur.
Here are a few examples:
● If I start eating healthier and exercise more, then I will lose weight.
● If I study for my history exam, then I will get a better grade.
● If we wash our hands frequently during flu season, then this will lower our risk of getting sick.
● If I start doing yoga once a day, then I will be more flexible by the end of this semester.
Conditional statements are often used in mathematical equations to logically predict outcomes where the variables might change. These equations utilize a hypothesis to arrive at a specific conclusion once the theory is tested. This type of logic is also often used with problem solving and critical thinking in a variety of subjects, such as psychology, math, chemistry, physics, business, philosophy, and so on.
When you’re writing your hypothesis, you’ll want to put it in these terms in order to establish the connection between the variables and the outcome you’re predicting will happen. We’ll talk more about variables later on in this article, but we need to learn more about the logic first. Ultimately, you should be able to break down the logic within your hypothesis to determine how you’ve reached your if, then this statement.
Going back to the previous example of sugary treats leading to strange dreams, your if, then this statement for your hypothesis would be as follows: if I stop eating sugary treats before bed, then I will stop having weird dreams. You can break down the logic of this statement easily: the sugary treats are the only thing you have changed during your night time routine within the last year, so therefore they are likely causing the difference in your sleep patterns.
College science student writing a hypothesis for his experiment on the lab computer
Coming up With a Good Hypothesis
You’ll never learn how to write a hypothesis if you don’t have a good idea in the first place, so that’s our next step.
Conduct some preliminary background research. This can be based on anything from common sense to something you saw in an academic journal. Has someone else produced an experiment you can use to inspire your own project? While you’re doing your background research, check out Episode 55 of the Homework Help Show, where our host Cath Anne shows you how to identify “bad science”!
Most of the time, a hypothesis is based on an observation. For example, in the 1600s, Sir Isaac Newton noticed an apple fall from a tree and made an observation that things always fell down toward the earth instead of in any other direction. With that observation, he formed a hypothesis that there was some type of pull coming from the alignment of the earth, and began to experiment with other objects. When his hypothesis was confirmed, his theory of gravity was born.
Think about the world around you and the problems you encounter regularly. Is there anything you can test to determine if a different result might occur? These types of questions can help you come up with a great idea for your experiment. Learn to think more critically about the world, and you’ll find that the observations come to you easier.
If your professor has assigned you a specific experiment to perform, it’s easier to come up with a hypothesis because you already have the groundwork done. In that case, all you have to do is figure out what variables to change and how you’ll attempt to replicate or produce certain results.
Biology students doing background research on different cells
Determining if Your Hypothesis is Testable
One of the most important aspects of a good hypothesis is that it has to be testable. This is a crucial aspect of the scientific method. If your hypothesis is not testable, the results of your experiment won’t prove anything, and since the entire point of your experiment is to prove something, you can’t get top marks with that approach.
Additionally, the entire point of creating a hypothesis is so that you can test it through your experiment or survey. If you don’t write a testable hypothesis, there will be nothing to test, and the entire point of your project is lost.
Here is the criteria to determine that your hypothesis is testable and can be used for your experiment or project:
● There’s a possibility that your hypothesis will be proven to be true.
● There’s a possibility that your hypothesis will be proven to be false.
● The results of your hypothesis can be reproduced again.
For the sake of learning how to write a hypothesis, let’s revisit that example from before where we hypothesized that eating sugar before bed causes strange dreams. This hypothesis is testable because you can easily add or remove the sugary treats before bed and record whether you experienced strange dreams or not.
Identifying The Variables
Variables are a key part when you develop a hypothesis. Every scientific experiment includes independent and dependent variables and relies on those to form a clear conclusion.
Dependent variable: The idea that you’re testing.
Independent variable: The factor that you’re changing to produce results.
You need both of these variables in order to perform an experiment and prove a hypothesis. When you have one dependent variable that doesn’t change and another independent variable that does, it offers definite proof that the independent variable is causing the outcome. In other words, when you only change one thing in your experiment, you can make a clear connection that the specific thing that changed is the cause.
For example, if we go back to the sugar before bed hypothesis, we can break down the independent and dependent variables. The dependent variable is the strange dreams you’re having, while the independent variable is the snack you eat before bed because you’re going to be changing that snack to determine if it’s causing your dreams. If you changed both variables, such as eliminating the sugar and taking a nap instead of going into a deep sleep, you wouldn’t be able to determine that the sugar is directly leading to the dreams.
College science student performing a chemistry experiment in the lab
Types of Hypotheses
There are a few different types of hypotheses based on different factors, such as what part of the experiment you’re in or how many variables you’re using. The most common types of hypothesis are as follows:
Simple hypothesis: A hypothesis that predicts a relationship between the variables in the experiment. This is the most common type of hypothesis and likely the one you’ll use the most. Here is an example: If you drink sugary drinks every day, you are more likely to be overweight.
Complex hypothesis: Similar to a simple hypothesis, the complex hypothesis predicts a relationship between the variables in the experiment, but in this case, there are two or more of each type of variable. Here’s an example: People who are overweight and eat fatty foods have higher instances of heart disease and high cholesterol levels.
Null hypothesis: With a null hypothesis, the researcher is predicting that there is no relationship between the two variables. In other words, there won’t be a difference in the results of the experiment, and the experiment will be done in order to either disprove or reaffirm this idea. Here’s an example: If I get six hours of sleep or eight hours of sleep there will be no difference in my work productivity for that day.
Alternative hypothesis: An alternative hypothesis usually develops in connection with a null hypothesis. It is a hypothesis that you might discover or propose while you’re trying to disprove a null hypothesis. You could also create an alternative hypothesis to replace another one you’re testing if you aren’t seeing results.
Nondirectional hypothesis: While it’s structured the same way as a simple hypothesis, a non-directional hypothesis does not specify the specific relationship between the two variables. For example, you might assume that the amount of water you give a plant has an impact on its growth, but you may not have an idea whether that will be a positive or negative result.
Logical hypothesis: A logical hypothesis is a hypothesis based on little to no substantial evidence for a particular prediction. Alternately, it’s rooted in logical connection and reasoning instead of background research. This type of hypothesis can be tested with certain resources, but remains as a logical statement or assumption until it is put to the test. Here’s an example: Dogs cannot survive without drinking water. This example is based on the assumption that because humans can’t survive without drinking water, most mammals won’t, either.
Empirical hypothesis: An empirical hypothesis is the term used to identify a hypothesis that is currently being tested or being adjusted according to the results of an experiment that is underway. It’s based on the trial and error of the experiment and the data being collected, and adjusts according to the information you’re seeing. In other words, it’s a working hypothesis.
Statistical hypothesis: A statistical hypothesis is based on data or statistics about a certain topic using a portion of a population or a sample size. It’s often used when collecting information about a population of people where it isn’t possible to survey or test every single person in that group.
Here are some examples of a statistical hypothesis (please note that all statistics below are completely fictional and are only being used as examples):
● 67% of marriages end in divorce.
● 75% of people living in Toronto take public transit to get to work every day.
● 60% of people who talk on their phone while driving have been in at least one car accident.
● 30% of the United States population is vegan.
Multiple female college students working together on a science experiment
Putting it Together: How to Write a Hypothesis in Three Main Steps
Here are the three main steps you should follow when you’re writing a hypothesis:
● 1. Determine and identify the problem you are trying to solve.
● 2. Create an “if, then, this” statement to write out your prediction.
● 3. Define your variables.
Let’s break those steps down a little further.
Determining and identifying the problem: Think about your research question and the observation you’ve made to create your hypothesis.
Creating an “if, then, this” statement: Write out your hypothesis as a statement – NOT a question. It should ideally be written in the “if, then this” verbiage so you can clearly identify how you’ve made your guess and what the variables are. Some hypotheses will be a little more complex than that, but you should be able to turn it into an “if, then this” statement from what you have written.
Defining your variables: Make sure your independent and dependent variables are clear in your written hypothesis statement. These are a key component of your “if, then, this” statement, so if you don’t see them in there go back and revisit step two.
Here is a written hypothesis statement for our sugar and strange dreams experiment:
“If an individual consumes excessive amounts of sugar in the hour or two before they go to sleep, then they will experience a higher occurrence of bizarre or strange dreams. Therefore, sugar consumption has a direct impact on the body’s REM sleep cycle.”
Again, you want to make sure your hypothesis is written as a statement because this is an educated guess that you’ve made based on your observations. You’re not going to lose marks if your experiment proves your hypothesis wrong, and a negative conclusion won’t impact whether your hypothesis is a good one or not. Instead, you’re going to be marked on whether your hypothesis meets the required criteria and guidelines we’ve outlined for you here.
Female scientist getting ready to perform an experiment in a white lab coat
A Hypothesis Creation Checklist
To sum up everything we’ve outlined above, we’ve put together this checklist you can follow when you’re learning how to write a hypothesis.
Ask yourself these questions to determine if you’re on the right track:
● Have you introduced your research topic or question?
● Can you easily identify your independent and dependent variables? Are they clear and understandable?
● Is your hypothesis testable?
● Have you written your hypothesis in clear, concise language that gets straight to the point?
● Did you outline your own expectations for what will happen during your experiment?
If you can say “yes” to all of the questions in this list, then your hypothesis is ready to go!
Ideas For Your Next Hypothesis or Scientific Experiment
Knowing how to write a hypothesis is only half the battle when it comes to completing a science project or paper. Deciding on what to do for your experiment is a major factor. At the university or college level, throwing together a baking soda volcano doesn’t cut it for a passable science project.
Here are some ideas and research questions you can try out for your next science project or experiment:
● Will a large presence of industrial factories in a specific community impact the water pollution levels in that community?
● Do students who skip class get lower grades than students who have perfect attendance?
● If temperature has an impact on plant growth, will exposing plants to warmer temperatures will cause them to grow faster?
● If you exercise once a day, will you lose weight faster than someone who doesn’t exercise at all?
● Are crime rates higher in areas with high unemployment rates?
● Will plants grow faster if you give them distilled water instead of tap water?
● Do students who take naps absorb information more efficiently than students who don’t nap at all?
If you’re still stuck for ideas, take a look at our list of 250 research topics for college students. You can take many of these topics and find an experiment based on them, or narrow them down to form a specific research question.
Two male scientists collecting data from an experiment outside
If You’re Ready to Give up on Learning How to Write a Hypothesis, Let us Help
Reading an article on how to write a hypothesis is one thing, but putting this into practice to get a good grade on your science project is another thing.
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