MA207 Final Exam - Takehome Portion
For each of the problems below, use the technology guide to perform a statistical analysis.
You should justify your choice of method, including any assumptions made in the use of the method.
You should indicate whether a two-tailed, left-tailed, or right-tailed analysis is appropriate,
and, in hypothesis testing problems, state the null and alternative hypotheses.
If the problem does not specify a level of significance, you should choose one.
Problem 1
In a double-blind study of Obsessive-Compulsive Disorder (OCD), 204 subjects with OCD are randomly divided into equal sized treatment and control groups. Subjects in one group are treated with cognitive behavior therapy (CBT) while the second group receives no treatment. After 12 weeks, 7 subjects
in the CBT group have experienced a remission of OCD, while 4 subjects in the placebo group have.
Can we conclude that patients receiving treatment are more likely to remit than those not receiving treatment?
Problem 2
In a study of the effect of long-term talk therapy on depression, 48 subjects diagnosed with
major depressive disorder (MDD) are given a modified version of the Beck Depression Inventory
(BDI) after six months and again after nine months of treatment. The mean difference between
the six month and nine month BDI scores was 3.2 with a standard deviation of 2.4. Does
this data support the claim that talk therapy beyond six months is not effective.
Problem 3
The DSM-IV Axis-V Global Assessment of Functioning Scale (GAF) is a widely used, global measure of psychological, social, and occupational functioning (American Psychiatric Association, 1994). In a longitudinal study, the mean GAF score for 56 subjects in the first year was 51.2.
Published data indicates that in the general population, the mean GAF score is 68.1 with a
standard deviation of 18.5. Can we conclude from this data that the study subjects score
significantly lower on the GAF than the general population?