Null refers to ‘no difference’. Null hypothesis is the hypothesis that there is no significant difference between specified populations, any observed difference being due to sampling or experimental error. The specified populations here are male and female students. A research hypothesis is a specific, clear, and testable proposition or predictive statement about the possible outcome of a scientific research study based on a particular property of a population. A directional hypothesis is a prediction made by a researcher regarding a positive or negative change, relationship, or difference between two variables of a population. A statistical hypothesis, sometimes called confirmatory data analysis, is a hypothesis that is testable on the basis of observing a process that is modelled via a set of random variables.