A research would like to analyze effects of humidity on eating behavior. It is known that laboratory rats normally eat an average of µ = 21 grams of food each day. Research chooses the random sample of n = 16 rats and places them in controlled atmosphere room in which relative humidity is maintained at 90%. Daily food consumption scores for rats are as follows:

14, 18, 21, 15, 18, 18, 21, 18
16, 20, 17, 19, 20, 17, 17, 19

a. Can researcher conclude that humidity has significant effect on eating behavior? Use a two-tail test with α = .05.

b. Calculate estimated Cohen's d and r2 to measure size of treatment effect.