# Mixed model adjusted for lme4

I am trying to fit a mixed model using the library lme4, and is emerging the following error.

fixed-effect model matrix is rank deficient so dropping 10 columns / coefficients.

In this case, I'm using the Effects window and time as factors. If they are considered numeric, the error becomes

fixed-effect model matrix is rank deficient so dropping 2 columns / coefficients.

Modelo1 <-lmer (EREF GROUP ~ + Time + window +
GROUP:Time +
GROUP:Window +
Time:Window + Time:Window:GROUP + (1 | Subject),
data = datalong2)


From what I see, it is not estimating doi elements of interaction between GROUP: WINDOW.

Does anyone have suggestions to solve this problem?

• Have you tried running lmer(EREF ~ Time + Window + GROUP:Time + GROUP:Window + Time:Window + Time:Window:GROUP + (1 | Subject), data = datalong2)? – Pavel Apr 22 '15 at 9:57
• Not yet, but I'll try. – Matheus Henrique Dal Molin Rib Apr 22 '15 at 12:17
• while framed as an R question, I believe the essential issue here is statistical. – Glen_b -Reinstate Monica Apr 23 '15 at 0:07

This looks like it's just a typo, i.e. specifying GROUP: + Window instead of GROUP:Window. It would be easier and less error-prone instead to specify ~Time*Window*GROUP-GROUP ... (are you sure you meant to leave out the main effect of GROUP?)