A cohort study to evaluate the effect of smoking on lung cancer (LC) produced the following results:
|
LC
|
No LC
|
|
Smokers
|
178
|
1129
|
|
Non-smokers
|
79
|
1262
|
The distribution of these people by age (less or more than 40 years old) is shown below:
Among younger than 40-years old:
|
LC
|
No LC
|
|
Smokers
|
168
|
880
|
|
Non-smokers
|
34
|
177
|
Among older than 40-years old:
|
LC
|
No LC
|
|
Smokers
|
10
|
249
|
|
Non-smokers
|
45
|
1085
|
Discuss if age is confounding the association between smoking and lung cancer in this study.