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From |
Fred Wolfe <fwolfe@arthritis-research.org> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
st: Comparing overlapping groups |

Date |
Tue, 2 Oct 2012 09:06:31 -0500 |

Dear Statalisters, I am analyzing a medical condition (FM) that has 4 different definitions for the same condition. A person can be in 1 or more of four definition defined groups (FM1, FM2, FM3, FM4). There are 2442 observations. I am interested the value of a dependent variable, phq_sss, according to each group definition. For the first two definitions, I get these results . regress phq_sss i.wsp Source | SS df MS Number of obs = 2442 -------------+------------------------------ F( 1, 2440) = 605.51 Model | 7621.27967 1 7621.27967 Prob > F = 0.0000 Residual | 30711.1417 2440 12.5865335 R-squared = 0.1988 -------------+------------------------------ Adj R-squared = 0.1985 Total | 38332.4214 2441 15.7035729 Root MSE = 3.5478 ------------------------------------------------------------------------------ phq_sss | Coef. Std. Err. t P>|t| [95% Conf. Interval] -------------+---------------------------------------------------------------- 1.wsp | 6.247731 .2538992 24.61 0.000 5.74985 6.745611 _cons | 2.728905 .0751615 36.31 0.000 2.581518 2.876292 ------------------------------------------------------------------------------ . regress phq_sss i.mwsp Source | SS df MS Number of obs = 2442 -------------+------------------------------ F( 1, 2440) = 229.25 Model | 3292.19831 1 3292.19831 Prob > F = 0.0000 Residual | 35040.2231 2440 14.3607472 R-squared = 0.0859 -------------+------------------------------ Adj R-squared = 0.0855 Total | 38332.4214 2441 15.7035729 Root MSE = 3.7896 ------------------------------------------------------------------------------ phq_sss | Coef. Std. Err. t P>|t| [95% Conf. Interval] -------------+---------------------------------------------------------------- 1.mwsp | 10.37138 .6849863 15.14 0.000 9.028161 11.71459 _cons | 3.144753 .0771774 40.75 0.000 2.993413 3.296093 ------------------------------------------------------------------------------ There are two additions definitions that are not shown. So the difference for group members as opposed to none groups members in the two analyses above is: wsp 6.2 mwsp 10.4 (there will be 2 other groups). My question is, how do i tell if the results are statistically different between the 4 groups, given the overlapping membership in the groups. I have a feeling that some sort of permutation test is the way to get such an answer. I'd appreciate suggestions. Thanks, Fred Fred Wolfe National Data Bank for Rheumatic Diseases Wichita, Kansas NDB Office +1 316 263 2125 Ext 0 Research Office +1 316 686 9195 fwolfe@arthritis-research.org * * 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: Comparing overlapping groups***From:*David Hoaglin <dchoaglin@gmail.com>

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