In a Longitudinal Study with Random Assignment to Treatment Groups

Multiple Choice

In a longitudinal study with random assignment to treatment groups, approximately 10 percent of the sample dropped out of the study early. Those who dropped out were similar to those who did not, and the percentage of dropped participants was roughly equal across conditions. In this example, the issue of participants leaving represents what potential problem(s) ?

A) mortality
B) systematic error
C) selection
D) parts A & C
E) all of the above
F) none of the above