A 1989 report of depression in adolescents (published inBehavioral Disorders) studied whether depression is associated with age group in adolescents.

In an observational study, 465 people were classified into one of three age groups, and one of two depression levels, as shown below (and also inFIGURE 34-A):

Thenullhypotheses being tested could be written as:

A.Thepercentageof adolescents with high depression is the same for all age groups, in thepopulation.

B.Thepopulation meanage is the same for all depression levels.

C.Nocorrelationexists between age and depression, in thesample.

D.Acorrelationexists between age and level of depression, in thepopulation.

E.Thepercentageof adolescents with high depression isnotthe same for all age groups, in thesample.