In the following example, what is the population parameter? Is the population parameter the mean of the population being tested?

The experiment consists of a psychologist trying to find out how accurately students can solve multiplication problems. To do this, the groups are divided in two ways: In the first is the type of reward, either a small reward or no reward, and the second is the amount practiced: either all training in one three hour session or training in one hour per day for three days. They are trying to find out whether the types of reward and the days practised affects how accurately students can solve the problems. What is the statistical test that you used to conduct this analysis?