Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.
| From | "Airey, David C" <david.airey@vanderbilt.edu> |
| To | "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu> |
| Subject | Re: st: Bootstrapped Paired-Samples (Dependent) T-Test |
| Date | Thu, 27 Jan 2011 11:36:12 -0600 |
. It is worth noting a couple different ways to doing the paired t-test then. clear set more off webuse fuel // note p = 0.046 in all tests below, and near this in bootstrap versions ttest mpg1==mpg2 // paired t-test gen diff = mpg2-mpg1 ttest diff == 0 // one sample t-test on differences bootstrap, reps(1000): regress diff // bootstrap of regression equivalent of one sample t-test gen pair = _n // needed for reshaping to long reshape long mpg, i(pair) j(time) // reshape to long anova mpg time pair // anova equivalent of paired t-test regress // show regression equivalent regress mpg i.time i.pair // do regression equivalent bootstrap, reps(1000): regress mpg time, vce(cluster pair) // bootstrap using cluster variable > Right, I think we are on the same page, but just to clarify: The issue here is that since the predictor variable is binary status in the matched pair (e.g., are you the pre or the post score for case 39), the data would be in long format with the two members of each matched pair falling in separate rows with an id variable indicating their shared membership in a common pair. The data found via sysuse bplong are illustrative. So, I believe this would need to be long format w/ resampling of clusters, but perhaps I'm missing something. > > Pair Score PrePost > 1 .8 0 > 1 .61 1 > 2 .4 1 > 2 .3 0 > ... > 54 .9 1 > 54 .4 0 > > > Thanks, > Rob * * 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/