Suppose you have data that looks like this The control group

Suppose you have data that looks like this:

The control groups adjusted post-test mean scores might turn out equal to which of these if the pre-test is used as a covariate? A. 5    B. 15    C. 25    D. 35    E. 45

Explain?

Solution

15

because

if pre test is used then

mean =(10+20)/2 =15