search for: asympot

Hello, I am interested in using nlme to model repeated measurements, but I don't seem to get good CIs. With the code below I tried to generate data sets according to the model given by equations (1.4) and (1.5) on pages 7 and 8 of Pinheiro and Bates 2000 (having chosen values for beta, sigma.b and sigma similar to those estimated in the text). For each data set I used lme() to fit a model,

Dear listers, I can't find the variance or se of the coefficients in a multilevel model using lme. I want to calculate a Chi square test statistics for the variability of the coefficients across levels. I have a simple 2-level problem, where I want to check weather a certain covariate varies across level 2 units. Pinheiro Bates suggest just looking at the intervals or doing a rather

...correct me if I'm wrong but I believe it is the matrix logarithm of Cholesky decomposition of the covariance matrix of the random effects. I believe the details are in the book by Pinheiro and Bates. Once you know the transformation you can use the "apVar" elements to get estimated asympotic standard errors for your variance components estimates using the delta method. J.R. Lockwood 412-683-2300 x4941 lockwood at rand.org http://www.rand.org/methodology/stat/members/lockwood/ ------------------------------ Message: 20 Date: Thu, 26 Jun 2003 10:58:01 -0400 From: Jean Eid <jeane...