David Heiser <[EMAIL PROTECTED]> wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Been doing a little cross checking between sources on the confidence > interval about sample means, where the sample (n) comes from a normal > population with unknown mean and unknown variance. > > Several textbooks give the confidence interval about the sample mean as > t*s/sqrt(n), where n is the number in the sample, t is the t distribution > value at n-1 df, and s is the sample unbiased standard deviation.
The usual s is *not* an unbiased estimate of sigma. Glen . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
