search for: 2cov

...itten for lmer(). The output for the fixed effects gives a standard error for the intercept, the coefficient of x and the correlation. For n observations, I transform the std errors to variances, and with the correlation, I think I can use the formula Var(intercept + x) = Var(intercept) + Var(x) + 2Cov(x,intercept) to get the variance of the fixed effects component of the response variable. However, I would like to include the random effects component of the variance, so I may derive a standard error and confidence interval for the variance. Does anyone know how to do this? Is there a ready mad...

...e curves of the point estimates of the time effect, including its interactions with other covariates. My question is about confidence bands. So far, I tried to calculate these in a straightforward manner using the coefficients' estimated covariance matrix. [ e.g., Var (a+b) = Var(a) + Var(b) + 2Cov(a,b) ] Common sense suggests that the bands will be narrowest in the middle of the time period studied and widening towards the edges. However, the model fit seems to default to zero time-effect errors at the start of the period, gradually widening as time progresses - which is not supported by th...