Researchers use hypotheses to test the relationship between factors or elements, also known as variables, in a scientific study. Hypotheses set the dependent variable, the factor that changes, and the independent variables, factors that influence the dependent variable, in the study.
For quantitative research, the hypothesis serves to formulate a test statistic, which is a mathematical way to find the accuracy of a hypothesis. The null hypothesis is the default hypothesis, and it states that there is no relationship between the dependent and independent variables. The alternate hypothesis, or research hypothesis, indicates there is a relationship between the variables. Researchers use means, proportions, probabilities and other statistical tests to determine the validity of the hypothesis.
When formulating a hypothesis, researchers use a formula that notes a cause-and-effect or if-then statement. An example of a hypothesis is that due to the effects of performance pressure, students with test anxiety have lower test scores. The independent variable is test anxiety, while the dependent variable is the test score. An example of a hypothesis in the physical sciences is that a certain gene increases the risk for breast cancer. Hypotheses come from observations, previous research, current literature in the field and personal experiences.