# coef() vs. ranef() using glmer in R

I am running mixed effects regression in R, utilizing glmer, and am hoping someone can help clarify the difference between using coef and ranef on the results. Specifically, I have fixed effects $f_1,f_2,f_3$ and random effects $r_1,r_2,r_3.$ When I run coef I get certain coefficent values for each of the fixed and random effects. Additionally when I use the ranef function I get coefficients for my random effects. These two coefficients are not equal for each respective random effect $r_1,r_2,r_3.$ Why are these coefficients different and what information each coefficient tells us?

• coef returns coefficients and ranef returns modes of random effects - what i not clear in it for you? – Tim Oct 20 '15 at 19:36
• @Tim Why doesn't coef = ranef. Shouldn't the coefficient = mode of random effect = mean of random effect? – OuijiBoard Oct 20 '15 at 19:41
• @Tim Then what information is being given to me when coef() returns a coefficient of a random effect? – OuijiBoard Oct 20 '15 at 19:47

coef: Computes the sum of the random and fixed effects coefficients for each explanatory variable for each level of each grouping factor
and ranef is