[R] Question on nlme

[Rui Barradas]

On 9/19/2025 2:36 PM, sasha a wrote:
> Hello,
> 
> I am using the nlme package in R:
> 
> model <- lme(
>      response ~ response_type + x_y + x_z - 1,
>      random = ~ response_type - 1 | group,
>      weights = varIdent(form = ~ 1 | response_type),
>      data = data_long,
>      control = lmeControl(opt = "optim")
> )
> 
> Is it possible to know what estimation process this is using? For example, is it using EM? Or is it use Newton-Raphson with GLS/RMLE?
> 
> Thanks!
> 
> 
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> 
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Hello,

I am not sure this answers the question but nlme::lme.formula 
optimization function defaults to ?optim, which defaults to method 
Nelder-Mead.
Users can change this via ?lmeControl, with two possible values for the 
method, ?nlminb and optim.

Hope this helps,

Rui Barradas