How do I extract lmer fixed effects by observation?

Question

I have a lme object, constructed from some repeated measures nutrient intake data (two 24-hour intake periods per RespondentID):

Male.lme2 <- lmer(BoxCoxXY ~          


        

Answer 1

It is going to be something like this (although you really should have given us the results of str(Male.Data) because model output does not tell us the factor levels for the baseline values:)

#First look at the coefficients
fixef(Male.lme2)

#Then do the calculations
fixef(Male.lme2)[`(Intercept)`] + 
c(0,fixef(Male.lme2)[2:4])[
          match(Male.Data$AgeFactor, c("1to3", "4to8", "9to13","14to18") )] + 
c(0,fixef(Male.lme2)[5])[
          match(Male.Data$IntakeDay, c("Day1Intake","Day2Intake") )]

You are basically running the original data through a match function to pick the correct coefficient(s) to add to the intercept ... which will be 0 if the data is the factor's base level (whose spelling I am guessing at.)

EDIT: I just noticed that you put a "-1" in the formula so perhaps all of your AgeFactor terms are listed in the output and you can tale out the 0 in the coefficient vector and the invented AgeFactor level in the match table vector.