Description
Applied Regression Analysis of Public Health Data
BST ? 63014 / 83014
Assignment – 1
Due in class (printed copy), February 03, 2022
This assignment is intended to help introduce you to the key concepts of Analysis of Variance (ANOVA),
and to understand the application of these tools in public health research.
Please be thorough but succinct and clear in writing. Provide SAS / SPSS / STATA program in Appendix.
I require you to turn in your assignment, typed in a word document. A printed copy of your assignment is
due in class. ASSIGNMENTS TUNRED IN PAST DUE DATE WILL NOT BE ACCEPTED FOR GRADE.
Should you have any questions while working on the assignment, please contact me (individual or working
group). I prefer you contact sooner than later.
One-way Analysis of Variance (ANOVA)
1. A new serotonin-update inhibiting agent, SN-X95, is being studied in subjects with general
anxiety disorder (GAD). Fifty seven subjects diagnosed with GAD of moderate or greater
severity consistent with the Diagnostic and Statistical Manual, 3rd edition (DSMIIIR) were
enrolled and randomly assigned to one of the 3 treatment groups: 25 mg SN-X95 (low
dose), 100 mg SN-X95 (high dose), or placebo. After 10 weeks of once-daily oral dosing in
a double-blind fashion, a test based on a Hamilton Rating Scale for Anxiety (HAM-A) was
administered. This test consists of 14 anxiety related items (e.g., ?anxious mood?,
?tension?, insomnia?, ?fears?, etc), each rated by the subject as ?not present?, ?mild?,
?moderate?, ?severe?, or ?very severe?. HAM-A test scores were found by summing the
coded values over all 14 items using the numeric coding scheme of 0 for ?not present?, 1
for ?mild?, 2 for ?moderate?, 3 for ?severe?, 4 for ?very severe?.
Page 1 of 3
Table: HAM-A Test Scores across all 3 Treatments.
HAM-A Test Scores Across Three Treatment Groups
Treatment
Low Dose
High Dose
Placebo
19
23
32
21
16
35
18
21
29
19
12
28
19
23
37
28
21
32
22
19
33
30
20
31
27
18
35
28
26
28
19
16
37
23
14
31
22
21
30
20
16
25
19
13
22
26
29
36
35
11
30
23
20
19
18
15
30
Based on the sample data provided, answer the following questions:
i.
ii.
iii.
iv.
Find the overall mean HAM-A test score. What is the interpretation of this overall
mean HAM-A test score?
Estimate the effect of each Treatment on HAM-A test score. Interpret the
estimated treatment effects.
Find the Mean Square Error (MSE) using the sample size and its corresponding
variance in each treatment group. What is the interpretation of MSE?
Construct a graph showing the box plots of HAM-A test Score, for each type of
treatment. Comment on the distribution of HAM-A test Score, for each type of
treatment.
Page 2 of 3
v.
vi.
vii.
viii.
ix.
x.
xi.
Construct a One-way ANOVA table for simultaneously comparing the mean HAMA test scores in the three treatment groups.
State your conclusion whether the mean HAM-A test scores in the three treatment
groups are similar or different. What information in the One-way ANOVA table did
you use to draw that conclusion? Does your conclusion agree with your
interpretation of the estimated treatment effects in part ii)? Explain.
Find the MSE in the ANOVA table constructed in part v).
Is the MSE in part iii) equal to MSE in part vii)? Explain.
Find the Mean Square Treatment (MST) in the ANOVA table constructed in part
v).
Comment on the comparison between MST and MSE in the ANOVA table
constructed in part v).
What assumptions did you make (you don?t have to formally test the
assumptions), if any, to perform One-way ANOVA for simultaneously comparing
the mean HAM-A test scores in the three treatment groups? Discuss any concerns
(you might have) with the data about the assumptions not being satisfied for
conducting One-way ANOVA, if formally tested.
Page 3 of 3
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