A Canadian study measuring depression level in teens (as reported in the Journal of Adolescence, vol. 25, 2002) randomly sampled 112 male teens and 101 female teens, and scored them on a common depression scale (higher score representing more depression). The researchers suspected that the mean depression score for male teens is higher than for female teens, and wanted to check whether data would support this hypothesis.
If μ1 and μ2 represent the mean depression score for male teens and female teens respectively, which of the following is an appropriate pair of hypotheses in this case? Check all that apply.
A. H0: µ1 - µ2 = 0
Ha: µ1 - µ2 < 0
B. H0: µ1 - µ2 > 0
Ha: µ1 - µ2 = 0
C. H0: µ1 = µ2
Ha: µ1 > µ2
D. H0: µ1 - µ2 = 0
Ha: µ1 - µ2 > 0