SRS = simple random sample. cheers Michelle
"Paul Bellamy" <[EMAIL PROTECTED]> wrote in message UD2t7.56886$[EMAIL PROTECTED]">news:UD2t7.56886$[EMAIL PROTECTED]... > Thanks alot - what does "SRS" mean? > Also what does "frequentist" mean - I have also seen that word? > > "Dennis Roberts" <[EMAIL PROTECTED]> wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > this is the typical margin of error formula for building a confidence > > interval were the sample mean is desired to be within a certain distance > of > > the population mean > > > > n = sample size > > z = z score from nd that will produce desired confidence level (usually > > 1.96 for 95% CI) > > e = margin of error > > > > so, typical CI for mu would be: > > > > samp mean +/- z times standard error of mean > > > > e or the margin of error here is z * stan error of the mean (let me > > symbolize se) > > > > e = z * se > > > > for 95% CI .. e = 1.96 * se > > > > e = 1.96 * (sigma / sqrt n) > > > > now, what n might it take to produce some e? we can rearrange the formula > ... > > > > sqrt n = (1.96 * sigma) / e > > > > but, we don't want sqrt n ... we WANT n! > > > > n = ((1.96 * sigma)/ e) ^2 > > > > so, what if we wanted to be within 3 points of mu with our sample mean the > > population standard deviation or sigma were 15? > > > > n = ((1.96 * 5) / 3)^2 = about 11 ... > > > > only would take a SRS of about 11 to be within 3 points of the true mu > > value in your 95% confidence interval > > > > unless i made a mistake someplace > > > > > > At 09:54 AM 9/28/01 -0400, Randy Poe wrote: > > >John Jackson wrote: > > > > > > > the forumla I was using was n = (Z?/e)^2 and attempting to express > .05 > > > as a > > > > fraction of a std dev. > > > > > >I think you posted that before, and it's still getting > > >garbled. We see a Z followed by a question mark, and > > >have no idea what was actually intended. > > > > > > - Randy > > > > > > > > >================================================================= > > >Instructions for joining and leaving this list and remarks about > > >the problem of INAPPROPRIATE MESSAGES are available at > > > http://jse.stat.ncsu.edu/ > > >================================================================= > > > > _________________________________________________________ > > dennis roberts, educational psychology, penn state university > > 208 cedar, AC 8148632401, mailto:[EMAIL PROTECTED] > > http://roberts.ed.psu.edu/users/droberts/drober~1.htm > > > > > > > > ================================================================= > > Instructions for joining and leaving this list and remarks about > > the problem of INAPPROPRIATE MESSAGES are available at > > http://jse.stat.ncsu.edu/ > > ================================================================= > > ================================================================= Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =================================================================
