You wish to conduct a case‐control study investigating the association between chewing betel quid (from the areca nut) and oral cancer in Kerala.You estimate that
The prevalence of betel quid use in the general population is 20% and based on
Previous studies you expect an odds ratio (OR) for oral cancer of OR=2.0 associated
With betel quid chewing compared to no betel quid chewing.Using the table below,
How large a sample (cases and controls) would you want for this study?
Table: Number of cases required for a case‐control study to detect a statistically
Significant association with varying levels of exposure prevalence1 Number of cases required (assuming 1 control per case), to achieve 80% power at =
0)05.

Question

You wish to conduct a case‐control study investigating the association between chewing betel quid (from the areca nut) and oral cancer in Kerala.You estimate that
The prevalence of betel quid use in the general population is 20% and based on
Previous studies you expect an odds ratio (OR) for oral cancer of OR=2.0 associated
With betel quid chewing compared to no betel quid chewing.Using the table below,
How large a sample (cases and controls) would you want for this study?
Table: Number of cases required for a case‐control study to detect a statistically
Significant association with varying levels of exposure prevalence1   Number of cases required (assuming 1 control per case), to achieve 80% power at  =
0)05.

Quizplus · Accepted Answer

The total sample size required is 338 (169 cases and 169 controls); the prime
assumption here is that your controls give a good representation of the source
population (ideally a random sample from that population), so their exposure
prevalence is close to 20%.

You Wish to Conduct a Case‐control Study Investigating the Association