A health psychologist seeks to predict compliance with medicalprescriptions using a self-report measure of methodicalness (M) anda health knowledge test (HK), the latter scored as pass (1) / fail(0). Out of 120 participants available at the study's outset, only30 are still involved at the 6-month point, when compliance (C) isassessed. Information on all three measures and theirinterrelationships is provided below.
     Time 1  Time2  Correlations/
     (N = 120)  (N = 30)  reliabilities*
     __________________  __________________  ______________________
  Measure  Range  Mean  SD  Mean  SD  M  HK  C
    Â
  Methodicalness  3 – 20  12.00  4.00  15.00  3.30   .82
  Health Knowledge  0 – 1  .50  .50  .80  .40  .32   .62
  Compliance  6 – 15        11.00  1.80  .40  .28   .72
    Â
  *Reliabilities are shown in bold.
a) What would be the observed criterion validity of the M scaleif the full range of M scores from time 1 was available forcorrelation with prescription compliance? Also, what explains thedrop in SD from T1 to T2? (3 pts.)
