Hi, I’m curious about how MixedModels.jl initialize model parameters for optimization.

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This template contains three types of elements: structural zeros (denoted by .), off- diagonal covariance parameters (initialized at 0), and diagonal variance parameters (initialized at 1).

Looks like they initialize like this: if the model has a random intercept and a random slope, then they would initialize the covariance matrix of the random effects using a 2 by 2 identify matrix. **Question 1: Is my understanding correct?**

By reading the code, it seems like this is where they initialize. But it looks like it only initializes the random effects part, not the fixed effect parameters. **Question 2: Did they leave the fixed effect parameters uninitialized (so the starting point will be picked by the solver)? Or am I missing anything?**