BootEff in psem with interaction terms

[AlexCarrascosa]

Hello¡
I'm trying to use the BootEff() function in a psem model composed of lmer models with some interaction terms (code attached at the end). I always get this error:

Warning message:
In (function (m, w) : 1001 model fit(s) or parameter estimation(s) failed. NAs reported/generated.

It seems that BootEff is not able to estimate these models. But, if I remove the interaction terms from the lmer models within the psem, it works perfectly. The problem is not related to random effects, because even with lm() models I get the same error when there are interaction terms.

Prod_psem <- psem(
lmer( Production ~ grass_proportion+
Treatment+Soil_fertility+Annual_Prep+
Treatment:Annual_Prep+
(1| Farm/Plot), data= Out_canopy_prod),

lmer( grass_proportion ~ Soil_fertility+Treatment+Mean_annual_Temp+
Annual_Prep+Treatment:Annual_Prep+
(1| Farm/Plot),data= Out_canopy_prod) ,

lmer(Soil_fertility ~ Treatment+
Mean_annual_Temp+(1| Farm),
data= Out_canopy_prod),
data = Out_canopy_prod)

Prod.sem.boot <- bootEff(Prod_psem, R = 1000, seed = 13, parallel = "snow", ran.eff = "Farm"))

Warning message:
In (function (m, w) :
1001 model fit(s) or parameter estimation(s) failed. NAs reported/generated.

I've also run the bootEff() including catch.err = FALSE and this is the error reported:

Error in contr.sum(levels(i)) :
not enough degrees of freedom to define contrasts

What goes wrong?

Thank you very much

[murphymv]

Hi Alex,

Without the data it's difficult to be certain what's going on. Is it possible to give the output of str(Out_canopy_prod)?

Regards,
Mark