Posttest-only control groups are not commonly used because
a) They only require one experimental group.
b) They do not control for threats to internal validity.
c) Test sensitization problems
d) They cannot expose a before and after picture.
Question 2
Posttest-only control groups are used to
a) Reduce reactivity to a pretest
b) Determine the effect of a treatment on a control group
c) Establish the strength of the posttest measure
d) Evaluate randomized controlled trials