If we collect information on students' study practices and exam scores and find strong evidence of a positive association between not studying more than two hours and high grades, when can we generalize this finding to the general population?

A student list for the college was obtained and students were randomly selected from the list to participate.

Explanation:

When the we select them randomly based on the test subject population, we can make a safe assumption that those random selection actually represent the real life demographic of the general population. If we select them manually, we will create a risk of biased pick  (the selected could have similar characteristics that the researchers personally like)

this null effect is caused by a weak manipulation and ineffective internal validity. in a scientific study, as the one dr. morimoto is trying to perfom, internal validity refers to the confidence placed in the cause-effect relationship and to how well an experiment is done and able to eliminate confounding variables.        

answer; cultural trait;