HW 7 Grading Key (Due 11/22/05)

[5 pts] t test printout, as requested on p. 40 of the Lab Workbook -- note that each student should have different results -- late printouts will be accepted with a flat deduction of 2 points.
[5 pts]  7.2 Placebo effect 

(a) These are paired samples because each data point in the placebo-treated sample is matched to a unique point in the control sample.
(b) Significance test

  • H0: �d = 0 vs. H1: �d 0
  • Test statistic
    • sem = 0.181 / sqrt(6) = 0.0739
    • tstat = (d - �0 ) / sem = ( -0.326 - 0 ) / 0.0739 = -4.41
    • df  = 6 - 1 = 5
  • One-tailed p is between .005 and .001. The two-tailed p is between .01 and .002. (Exact p is .0069.) These results are highly significant.
7.3 (part a): Oral contraceptives - posted
7.5 Water fluoridation - posted
P.1 Power. answer included with problem