Thank you Bruce.

I wonder if there any web site of macro that can perform those calculation form me.. when I know the levels and sizes And you're rigth I can omit 'pat' from 'medida By pat trat' Thank

Bruce Weaver escribió: > amllistas wrote: > >> Hello List. >> Now I'm wondering how to compute the POWER of a mixed model test.... >> The think is how to evaluate how good is it or if a would need to sample >> more (ufff!!!! very expensive and tedious, but if with 4 o 5 more i >> increase the power a lot i can consider it). >> >> Thank you all in advance. >> >> Finally , my syntax looks is like this: >> >> MIXED >> medida BY pat trat >> /CRITERIA = CIN(95) MXITER(100) MXSTEP(5) SCORING(1) >> SINGULAR(0.000000000001) HCONVERGE(0, ABSOLUTE) LCONVERGE(0, ABSOLUTE) >> PCONVERGE(0.000001, ABSOLUTE) >> /FIXED = trat | SSTYPE(3) >> /METHOD = REML >> /PRINT = SOLUTION TESTCOV >> /RANDOM INTERCEPT trat | SUBJECT(pat) COVTYPE(VC) >> /EMMEANS = TABLES(trat) COMPARE ADJ(BONFERRONI) . >> >> and my data like this (tab separated, and a dot as decimal): >> >> trat pat medida >> 1 1 4 >> 1 2 10 >> >> --- snip --- >> >> > > If you are asking how to compute post-hoc power, I would advise you not to > bother, as post-hoc power is just a transformation of the p-value. I.e., if > p < .05, you will find that post-hoc power was adequate, and if p > .05, > you'll find it was inadequate. > > If you are asking how to compute an a priori sample size estimate for a > multilevel (linear) regression model, take a look at Chapter 8 in Jos > Twisk's book, Applied Multilevel Analysis. It boils down to computing a > standard sample size estimate, and then applying a "correction factor", > which takes into account the multilevel nature of the data. However, there > are two possible correction factors. Twisk describes one as "liberal", and > the other as "conservative". He discusses the relative merits of the two, > and the situations in which they might be appropriate. He concludes: > > "In practice, the 'conservative' sample size procedure is mostly used. > However, most researchers do not reealise that this procedure leads to an > overestimation of the required sample size when the randomisation is > performed on the patient level." (Twisk 2006, pp. 130-131) > > p.s. - In your MIXED syntax, I believe you can omit "pat" from "medida BY > pat trat". > > > ----- > -- > Bruce Weaver > bweaver@lakeheadu.ca > http://sites.google.com/a/lakeheadu.ca/bweaver/ > "When all else fails, RTFM." > > NOTE: My Hotmail account is not monitored regularly. > To send me an e-mail, please use the address shown above. > -- > View this message in context: http://old.nabble.com/2-ways-MANOVA--or-what--and-how...-tp26791541p27652620.html > Sent from the SPSSX Discussion mailing list archive at Nabble.com. > > ===================== > To manage your subscription to SPSSX-L, send a message to > LISTSERV@LISTSERV.UGA.EDU (not to SPSSX-L), with no body text except the > command. To leave the list, send the command > SIGNOFF SPSSX-L > For a list of commands to manage subscriptions, send the command > INFO REFCARD > >

--

Antonio. Gracias, Efharisto poli, Grazie, Thank you, Tak, Shukran, Hvala, Blagodaria, Bedankt, Danke schön, Shukriya, Tesekuler, Merci, Spasiba, Obrigato, Go raibh maith agat, Arigato, Dishklenle, Dankon, Tashakkur

===================== To manage your subscription to SPSSX-L, send a message to LISTSERV@LISTSERV.UGA.EDU (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD