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From |
"Joseph Coveney" <stajc2@gmail.com> |

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

Subject |
st: Re: Re: Repeated Measures ANOVA: contrasts |

Date |
Sun, 2 Feb 2014 18:36:29 +0900 |

David C Airey wrote: I didn't read far enough in the help file! Page 362 and beyond for -contrast- has examples with evaluated fractions like `=1/3' in the linear combination. -------------------------------------------------------------------------------- I didn't read that far either. Anyway, if there is substantial autocorrelation, and if the difference between the average of the first two observations and the following three is of primary scientific interest, then the original poster would perhaps be better off just computing the averages for each volunteer and performing a paired t-test. -manova- and -manovatest- (or -contrast-) are out, with eight volunteers and seven intervals. Joseph Coveney . set seed `=date("2014-02-02", "YMD")' . . program define simem, rclass 1. version 12.1 2. syntax 3. . drop _all 4. set obs 8 5. generate byte pid = _n 6. generate double fmt1 = rnormal() 7. forvalues i = 2/7 { 8. generate double fmt`i' = 0.5 * fmt`=`i'-1' + /// > sqrt(0.75) * rnormal() 9. } 10. tempvar a b 11. generate double `a' = (fmt1 + fmt2) / 2 12. generate double `b' = (fmt3 + fmt4 + fmt5) / 3 13. ttest `a' = `b' 14. tempname p 15. scalar define `p' = r(p) 16. drop `a' `b' 17. quietly reshape long fmt, i(pid) j(time) 18. xtreg fmt i.time, i(pid) fe 19. test (1.time + 2.time) / 2 = (3.time + 4.time + 5.time) / 3 20. return scalar l = r(p) 21. return scalar t = `p' 22. end . . simulate t = r(t) l = r(l), reps(10000) nodots: simem command: simem t: r(t) l: r(l) . . foreach var of varlist l t { 2. generate byte pos_`var' = `var' < 0.05 3. } . . summarize pos_* Variable | Obs Mean Std. Dev. Min Max -------------+-------------------------------------------------------- pos_l | 10000 .105 .3065687 0 1 pos_t | 10000 .0511 .2202127 0 1 . . exit end of do-file * * 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: Re: Re: Repeated Measures ANOVA: contrasts***From:*Vincent Koppelmans <vkoppel@umich.edu>

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