Comments on: A primer on power http://www.smallgraymatters.com/2006/12/04/a-primer-on-power/ of brains and their minds Tue, 03 Aug 2010 21:30:01 -0700 http://wordpress.org/?v=2.8.4 hourly 1 By: Dan http://www.smallgraymatters.com/2006/12/04/a-primer-on-power/comment-page-1/#comment-12992 Dan Tue, 03 Aug 2010 21:30:01 +0000 http://www.smallgraymatters.com/2006/12/04/a-primer-on-power/#comment-12992 Dear Sir, I used your information while trying to validate my sampling population (in medical imaging indeed) for a computer-aided detection system. I tried to reproduce your following example: "If the correlation between mood and television watching in the general population is large (canonically, around r = .5), we’re only going to need 29 people to have an 80% chance of detecting it with p<0.05" .... However, doing the math I found that a minimum of 50 people would be needed. I based my calculation on saying that the 0.05False-Positive shall be represented by at least 1 people. Would you please be kind enough to provide your math please. Best regards, Dear Sir,
I used your information while trying to validate my sampling population (in medical imaging indeed) for a computer-aided detection system.

I tried to reproduce your following example: “If the correlation between mood and television watching in the general population is large (canonically, around r = .5), we’re only going to need 29 people to have an 80% chance of detecting it with p<0.05" ….

However, doing the math I found that a minimum of 50 people would be needed. I based my calculation on saying that the 0.05False-Positive shall be represented by at least 1 people.

Would you please be kind enough to provide your math please.
Best regards,

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