17 Apr Non-smokers Smokers ? CAD No CAD CAD No CAD ? High coffee 40 90 High coffee 150 65 ? Low coffee 65 150 Low coffee 45 20 ?
Non-smokers
Smokers
CAD
No CAD
CAD
No CAD
High coffee
40
90
High coffee
150
65
Low coffee
65
150
Low coffee
45
20
(a) Calculate the crude odds ratio (for the association of coffee drinking and CAD) and the two stratum-specific odds ratios. Show your calculations. (3 pts)
(b) Next assess whether:
i. smoking is related to coffee consumption among those without CAD.
ii. smoking is related to CAD among subjects with low coffee consumption
Show the new 2×2 tables for these relationships and your calculations for the stratum specific ORs for the new tables. (4 pts)
(c) If you knew nothing else about this clinical/biological system, are the data given in the question and your calculations in item (b) sufficient evidence for you to conclude that smoking is a confounder in the relationship between coffee use and CAD? Explain the rational behind your answer.
