The null hypothesis should be that the population mean difference is zero expressed as:
How to find the Null hypothesis?
The null hypothesis for investigating the effectiveness of a course by calculating the average difference in student scores on a test that is administered both before and after the course would be that there is no significant difference in the population mean scores before and after the course. In statistical terms, this can be expressed as "the population mean difference is zero."
This hypothesis is typically denoted as:
where
is the null hypothesis and
is the population mean difference in scores before and after the course.