Null Hypothesis

A null hypothesis is one in which no difference (or no effect) between two or more variables is anticipated by the researchers. This follows from the tenets of science in which empirical evidence must be found to disprove the null hypothesis before one can claim support for an alternative hypothesis that states there is in fact some reliable difference (or effect) in whatever is being studied. The null hypothesis is typically stated in words to the effect that "A equals B." The concept of the null hypothesis is a central part of formal hypothesis testing.

An example in survey research would be a split-half experiment that is used to test whether the order of two question sequences within a questionnaire affects the answers given to the ...