posted by Anonymous .
A school counselor tests the level of depression in fourth graders in a particular class of 20 students. The counselor wants to know whether the kind of students in this class differs from that of fourth graders in general at her school. On the test, a score of 10 indicates severe depression, while a score of 0 indicates no depression. From reports, she is able to find out about past testing. Fourth graders at her school usually score 5 on the scale, but the variation is not known. Her sample of 20 fiftsh graders has a mean depression score of 4.4.
Suppose the counselor tested the null hypothesis that fourth graders in this class were less depressed than those at the school generally. She figures her t scores to be -.20. What decision should she make regarding the null hypothesis
If she has the mean for fourth graders, why does she get a sample of fifth graders? How does she get a t value without any indication of variation from the sample?
To be significant at P = .05, t with 19 or (n-1) df, you would need a value of 2.093.
What would you conclude?