[R-sig-ME] Need help on convergence issue when fitting zero-inflated Poisson with random coefficients using gamlss

[Xia Li]

Hello,

I have trouble getting convergence when fitting ZIP with (individual level)
random coefficients, the function that I used:

m1 <- gamlss(y ~ re(fixed = ~ treatment, random = ~ treatment|unit_id),
             family = ZIP, data = dat)

Specifically I wanted to include global or population level treatment
effect, and individual random effect nested under treatment.

I always got the following error messages:

Error in lme.formula(fixed = fix.formula, data = Data, random = random, :
   nlminb problem, convergence error code = 1
   message = iteration limit reached without convergence (10)

Is there anything that I can debug from? Changing the control parameters? I
tried different algorithms like method = CG() but seems it did not help
much.

Looking for help. Thanks!

-- 
Best,
Xia

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