Name __________________

                                               

 

1) For a case-control study of resistant TB and HLA type AB, the cases and controls were matched on ethnicity. The results are in the following table:

 

 

Control HLA AB

Control not AB

Case HLA not AB

25

39

Case HLA AB

47

75

 

a) Compute the odds ratio; what does it mean?

 

b) Test the odds ratio; what is the null hypothesis you are testing?

 

c) Estimate the odds ratio’s confidence interval.

 

2) A case-control study of regular exposure to second hand smoke (y/n) and endometrial cancer needs to be adjusted for the age of the women involved. The tables split by age group are below:

 

Age 18-35

E. Cancer -

E. Cancer +

Exposure -

15

50

Exposure +

30

25

 

 

Age 36-55

E. Cancer -

E. Cancer +

Exposure -

30

25

Exposure +

15

50

 

a) What would be the odds ratio for each age group?

 

b) What do they mean in words?

 

c) Compute the adjusted odds ratio?

 

d) How would you report results and what are your conclusions?

 

3) Suppose you have the following two-by-four table of a disease versus age groups based on a case-control study:

 

 

18-25

26-35

36-45

45+

Disease -

777

301

1243

123

Disease +

189

91

355

60

 

Answer whether disease rates are different across groups? Which rates are different?

 

Perform proper test(s), estimation and interpret the results.

 

4) Suppose the results of a simple logistic regression are represented in the following STATA output:

 

 

Write the model equation which associated with this logistic regression, explain all terms in the model. Explain meaning of all the numbers in the output. Calculate OR if age is increased by 12 years (measurement unit is 1 year for the age variable) and find 95% confidence interval for that.

 

5) Explain the output and find OR to develop CHD between groups 1 and 4.