Hi Camila, In mixed equation form instead of multilevel, it would be:
Y_it = gamma_00 + gamma_10*X_it + gamma_11*W_it*X + (e_it + u_0t + u_1j*X) your code seems reasonable. Note that the random intercept and slope will be correlated in your specification (unstructured if you want, it is possible to force out, but is sensible starting place) model <- lmer(Y ~ X + X:W + (X | ID), data = data) which gives: residual variance: e_it variance of intercept (constant term, gamma_00): u_0t variance of slope (gamma_10): u_1j*X as well as overall estimates for the intercept, slope of X, and the interaction of X and W. Bert is correct that R sig mixed models is the more appropriate list, but many people read both and there is no reason it cannot be answered here. Cheers, Josh On Mon, Jul 2, 2012 at 6:47 PM, Camila Mendes <cacamende...@gmail.com> wrote: > Hey all - > > I am a newbie on mixed-effects models. I want to estimate the following > model: > > Y_it = alpha_0t + alpha_1t*X_it + e_it > alpha_0t = gamma_00 + u_0t > alpha_1t = gamma_10 + gamma_11*W_it + u_1j > > Where Y is my outcome, X is my level-1 predictor, and W is my level 2 > predictor. > > I am not sure if I am doing it right. Is this the correct specification of > the formula? > > model = lmer(Y ~ X + X:Y + ( X | ID), data = data) > > Also, can you help me to write down the combined model formula? I tried > by substituting on the first equation, but I got some weird interactions > with the residual (?) > > Thanks a lot! > > - Camila > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- Joshua Wiley Ph.D. Student, Health Psychology Programmer Analyst II, Statistical Consulting Group University of California, Los Angeles https://joshuawiley.com/ ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
