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#1
08-03-2011
 USMLE Forums Guru Steps History: Not yet Posts: 324 Threads: 70 Thanked 239 Times in 144 Posts Reputation: 249
Confidence Interval and Sample Size..

How sample size effect the Confidence interval?How sample size or population effect the increase or decrease in Confidence interval?

#2
08-03-2011
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 1,357 Threads: 194 Thanked 3,269 Times in 881 Posts Reputation: 3279

Quote:
 Originally Posted by struggle How sample size effect the Confidence interval?How sample size or population effect the increase or decrease in Confidence interval? Please explain anyone..
x%CI for the mean = mean + or - [Z score * SEM]

SEM = sd / square root of n

(assuming we know the sd....otherwise, follows a t distribution)
 The above post was thanked by: struggle (08-03-2011)

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