Dear Statalist,
I apologise; I was forgetting basic algebra. All I had to do to calculate the necessary number was to figure out that the power = 1-((1-P)^n), where n is the number of people you'd need to sample. Best regards,
Paddy
----- Original Message ----
From: Paddy Woodburn <[email protected]>
To: [email protected]
Sent: Mon, 30 November, 2009 15:57:13
Subject: Sample size to detect a rare response
Dear Statalist,
If you wanted 90% power to detect at least one positive result for a rare condition (expected proportion P) in a population, how would you calculate how many people you would need to test? Is there a command for this?
Best regards,
Paddy
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