There're several advantages of using paired t-test. Since same subjects are being tested in each of the varying situations, those subjects serve as their own control. This is the major advantage as you need not consider potential differences between subjects in the control group and the subjects who are in the experimental group. Elaborate on this concept by providing examples in which you do and do not have the same subjects serving as their own control.
There are also potential problems associated with interpreting the results of a paired t-test. Imagine you are interested in determining whether an employee of a company performs better with or without a bonus. What are some issues that could affect the results if you have the same subjects tested in both situations