A serious weakness of the pretest-posttest, natural control-group ...

[strangeaffliction]

A serious weakness of the pretest-posttest, natural control-group design is that
 
  A) the two groups may be statistically different from each other at the start of the study.
  B) the two groups may be statistically equivalent at the start of the study.
  C) experimenter effects cannot be prevented.
  D) there is no control for effects due to history or maturation.

Question 2

In a pretest-posttest, natural control-group design, the experimental and control groups are ________ at the beginning of the experiment.
 
  A) equivalent
  B) not equivalent
  C) matched
  D) Could be either A or B
 
  Fill in the blank with the correct answer.

[joewallace]

Answer to Question 1

Answer: A

Answer to Question 2

Answer: D

[strangeaffliction]

Excellent

[daiying98]

Gracias!