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From |
Amy Hsin <hsin.amy@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: generating predicted values for growth models |

Date |
Fri, 29 Jun 2012 17:01:03 +0200 |

Sorry, I re-ran it exactly as you did and it worked. But what is the difference between what I wrote: xtmixed gpach i.wave##i.asian i.wave##i.female i.wave##c.psescomk8 if gpachmiss!=1 || id: wave , cov(unstructured) variance emiterate(250) mle; And what you wrote: xtmixed gpach i.wave##(i.race i.female c.psescomk8) <other stuff> Are they not the same? Amy On Fri, Jun 29, 2012 at 4:53 PM, Amy Hsin <hsin.amy@gmail.com> wrote: > H Maarten, > > Thanks! That was helpful. However, I still encounter the same problem > when I revise the code. > > Now the command is the following. However, the predicted values > remain unchanged (i.e. they are the same as the observed). Any > suggestions? > > > > margins, over(asian wave); > > > Thank you, > Amy > > On Fri, Jun 29, 2012 at 4:23 PM, Maarten Buis <maartenlbuis@gmail.com> wrote: >> One thing you did wrong is that you used the -xi:- prefix and the >> -margins- post-estimation command. -margins- needs to know about the >> interactions you created, and -xi:- will does not leave that >> information behind. So you need to use the factor variable notation >> instead, see -help fvvarlist-. Translating your command would be: >> >> xtmixed gpach i.wave##(i.race i.female c.psescomk8) <other stuff> >> >> -- Maarten >> >> On Fri, Jun 29, 2012 at 4:03 PM, Amy Hsin wrote: >>> Hi, >>> >>> I am trying to generate predicted values from linear growth curves and >>> am running into problems. The predicted values that I am generating >>> using models that adjusts for a variety of covariates are the same as >>> the observed values, which does not make sense. Is there something >>> that I am obviously doing wrong? >>> >>> Here is a simplified version of my model. >>> >>> xi: xtmixed gpach i.wave*race i.wave*female i.wave*psescomk8 if >>> gpachmiss!=1 || id: wave , cov(unstructured) variance emiterate(250) >>> mle; >>> margins, over(race wave); >>> >>> -gpach are test scores evaluated at time 0, 1, 2 and 3 >>> -race and female are both dichotomous variables >>> -psescomk8 a time invariant continuous covariate >>> In this model, I'd like to measure time nonparametrically so I am >>> including it as a series of dummy variables. >>> When I use the "margins" command to estimate predicted test scores for >>> each racial category at each point in time, I get values that are >>> identical to the observed values. >>> >>> Any ideas as to what I am doing wrong? >>> >>> Thank you in advance. >>> >>> >>> Amy Hsin >>> * >>> * 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/ >> >> >> >> -- >> -------------------------- >> Maarten L. Buis >> Institut fuer Soziologie >> Universitaet Tuebingen >> Wilhelmstrasse 36 >> 72074 Tuebingen >> Germany >> >> >> http://www.maartenbuis.nl >> -------------------------- >> >> * >> * 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/ > > > > -- > Amy Hsin > Assistant Professor of Sociology > Queens College, City University of New York > http://qcpages.qc.cuny.edu/~ahsin -- Amy Hsin Assistant Professor of Sociology Queens College, City University of New York http://qcpages.qc.cuny.edu/~ahsin * * 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/

**Follow-Ups**:**Re: st: generating predicted values for growth models***From:*William Buchanan <william@williambuchanan.net>

**References**:**st: generating predicted values for growth models***From:*Amy Hsin <hsin.amy@gmail.com>

**Re: st: generating predicted values for growth models***From:*Maarten Buis <maartenlbuis@gmail.com>

**Re: st: generating predicted values for growth models***From:*Amy Hsin <hsin.amy@gmail.com>

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