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From |
Maarten buis <maartenbuis@yahoo.co.uk> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: estimate 95%CIs of the mean for different sample sizes |

Date |
Thu, 10 Jun 2010 03:42:50 -0700 (PDT) |

--- On Thu, 10/6/10, Miranda Kim wrote: > I have data for a sample of 300 which is approximately > normally distributed (slightly skewed). I would like to > derive 95% confidence intervals around the estimate of the > mean for sample sizes of 50, 80, 100, 150, and 400. > Does anyone have any suggestions what command I can use to > do this? Here is one approach: *----------------------- begin example --------------------- program drop _all *! version 1.0.0 MLB 10Jun2010 program define counterci, rclass syntax varname [if] [in], /// n(numlist) [level(real `c(level)')] marksample touse qui sum `varlist' if `touse' tempname se df lev res matrix `res' = J(`: word count `n'', 2, .) matrix rownames `res' = `n' matrix colnames `res' = lb ub local i = 1 foreach nobs of local n { scalar `se' = r(sd)/sqrt(`nobs') scalar `df' = `nobs' - 1 scalar `lev' = (100 - `level') / 200 matrix `res'[`i', 1] = /// r(mean) - invttail(`df',`lev')*`se', /// r(mean) + invttail(`df',`lev')*`se' local ++i } matlist `res' return matrix res = `res' end sysuse auto, clear counterci gear_ratio, n(20 50 100) *---------------------- end example -------------------------- (For more on examples I sent to the Statalist see: http://www.maartenbuis.nl/example_faq ) Hope this helps, Maarten -------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://www.maartenbuis.nl -------------------------- * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: estimate 95%CIs of the mean for different sample sizes***From:*Miranda Kim <mirandakim@hotmail.co.uk>

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