PSM
Biostatistics
The risk factor association of smoking with pancreatic cancer was studied in a case control study, the values which were found were:
Odd’s ratio 95% C.I
Group A 2.5 1.1 – 3.1
Group B 2.0 1.1 – 2.0
Group C 1.0 0.5 – 1.0
Which is true:
A  Risk is associated more with Group A

B  Risk is associated more with Group B

C  Risk is associated more with Group C

D  Risk is equally associated with the three groups

Ref: High Yield Biostatistics, Pg: 66
a. Please remember as a dictum, whenever the confidence interval of an Odd’s ratio or Relative risk contains 1 in the interval there is no association. So assertion C is a wrong option. Since the OR is different for the three groups, their risk of causing pancreatic cancer is also different, hence assertion D is also wrong option.
b. To decide between options A & B look at their OR which is a measure of strength of association and not their confidence interval if 1 is not included within the interval. Since the OR for Group A is higher, risk of association with pancreatic cancer is higher.
Biostatistics Flashcard List
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