[R-sig-ME] Question regarding large data.frame in LMER?

[João Veríssimo]

My comment about using poly(Age, 2) instead of I(Age^2) was a
suggestion for trying orthogonal polynomials specifically (i.e., not
raw=T but the default which is raw=F).

The reason is that Age and Age^2 will be very highly correlated,
whereas the linear and non-linear part of poly(Age, 2) are not
correlated.

Can't say if it'll help with your issue, though.

On Mon, 2020-12-14 at 16:00 +0000, Jad Moawad wrote:
> Thanks a lot everyone for all the suggestions you have provided, I
> really appreciate it. I have some replies over some comments and will
> write what have worked so far.
> 
> 
> 
> 1)    If understood well the comment regarding the duplicates, there
> was already no id that has the same number twice across different
> countries and years.
> 
> 2)    I switched the data.frame from tibble to as.dataframe.
> 
> 3)    I use now: poly(agecent, degree=2, raw=T) instead of I(age^2).
> 
> 4)    I tried centering, scaling and/or standardizing my variables
> but this have not solved the issue.
> 
> 5)    Regarding the question about how many country_years level I
> have. I have observations (1,150,110)  that are nested in *both*
> individuals (472,604) and country-years (180). In other words, they
> are cross-classified. In turn, individuals and country-years are
> *both* nested in countries (30). So the data structure is like a
> diamond, with a point (observatio