A researcher might choose to use a counterbalanced design when ...

[silviawilliams41]

A researcher might choose to use a counterbalanced design when
 
  a. the interactive effect of different treatments is to be examined.
  b. there is likely to be a carry-over effect of exposure to one treatment on a subsequent treatment.
  c. there is a likelihood of pretest sensitization.
  d. intact class groups are to be used.

Question 2

Assume you have developed a new instrument to measure introversion/extroversion in teachers. Would you assess score validity or reliability first? Why?
 
  What will be an ideal response?

[tdewitt]

Answer to Question 1

D

Answer to Question 2

One would want to establish validity first. If the test doesn't measure what it is supposed to measure, then it would not be useful regardless of its reliability.

[silviawilliams41]

Excellent

[xoxo123]

TYSM