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From |
"Fleming, Fiona M" <f.fleming@imperial.ac.uk> |

To |
"statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu> |

Subject |
st: Bootstrapping: Comparing the difference between means |

Date |
Wed, 3 Apr 2013 16:22:56 +0000 |

Hello, I am hoping someone can help! I have been trying to work out, all day, how I can perform a bootstrap on the mean difference of two samples. I have scoured the Statalist, FAQ etc to get ideas and have recently been trying to replicate the programming and commands illustrated in Example 2 on http://statistics.ats.ucla.edu/stat/stata/faq/ownboot.htm with my own data set i.e.: // step 1 ttest dcp if (del==1) + (del==2), by(del) return list matrix mu = (r(mu_1), r(mu_2)) matrix list mu // step 2 capture program drop mydiffa program define mydiffa, rclass preserve bsample ttest dcp if (del==1) + (del==2), by(del) estat mu return scalar diffa_1 = r(mu_1) return scalar diffa_2 = r(mu_2) restore end // step 3 simulate diffa_1=r(mu_1) diffa_2 = (r(mu_2), reps(100) seed(12345): mydiffa bstat, stat (mu) n(200) estat bootstrap, all after running this 'simulate' I get the following error and cannot proceed- '' found where ':' expected r(198); Please could you offer any advice as to what I am doing wrong? In addition, what I have written above will only give me the bootstrap SE and CI for each of the means and not the difference of the means, if you have any further advice on how I might run that I would be extremely grateful. Many thanks Fiona Fleming E-mail: f.fleming@imperial.ac.uk * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: Bootstrapping: Comparing the difference between means***From:*Scott Merryman <scott.merryman@gmail.com>

**Re: st: Bootstrapping: Comparing the difference between means***From:*Nick Cox <njcoxstata@gmail.com>

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