Forum: open-discussion

Standard error bands? [ Reply ]
By: Ben Amsel on 2009-05-08 14:52

Hello,

Given a quadratic mixed effects model (where t=time):
y = b0 + b1(x) + b2(t) + b3(t^2) + b4(x*t) + b5(x*t^2) + u + e,

the partial effect (assuming there were more predictors than shown above) of x on y is given by
dy/dx = b1 + b4(t) + b5(t^2)

I want to plot this function over time, and add a standard error band around this function.

I've noticed the use of standard error bands in some other packages (eg, SemiPar); does anybody know if obtaining these bands is possible within lme?

Thank you very much
Ben