Hypothesis Definition

What is a Hypothesis?

A hypothesis is an educated guess of why something is the way we observe in the world. We test that educated guess using experiments. Then we ask was our educated guess supported by our test or was the guess wrong and we go back to not understanding the observed phenomena.

You can think about a hypothesis two equivalent ways.

(1). A hypothesis follows the form if...then...because
~ or if you prefer ~
(2). A hypothesis is a "prediction generator," which works like this:

1. We observe something (students A performed better on tests than students B)
2. Why would that be? We come up with a hypothesis/explanation/educated guess (students who eat breakfast perform better on tests)--...and here's where we generate the prediction:
3. Therefore we predict something testable (So if students eat breakfast, then those students will do better on a test.)
4. Run an experiment by giving granola bars to a random half of the students, then measure their test scores.

The two ways of thinking about hypothesis are equivalent. Try substituting the breakfast/test example into the "If...then...because" format:

(first the prediction) IF a student eats breakfast, THEN the student will before better than students without breakfast (here comes the hypothesis) BECAUSE students who eat breakfast perform better on tests.

Some ecology students used the terms independent and dependent variable in their definitions. These are important scientific terms which you may know already. Here's a review.

1. independent variable: the CAUSE, such as eating breakfast, from the example above
2. dependent variable: the EFFECT or what we're measuring. The students' test scores from above. We're testing whether the dependent variable depends on the independent variable.