I’ve got a dataset that has temperature (21c or 29c), inoculation (mock (m),single inoculations (c or r), or coinoculation (rc)), and age group (y or o). I am trying to model the interactive effects of temperature, age group, and inoculation on the area under the disease progression stairs (audps) using the glmmTMB package in R as follows:

library(glmmTMB)
glm_model3<-glmmTMB(audps ~ temp * age_gp * inoc+(1|replicate), family = t_family, data = audps_data2)
glm_model3

I had gotten the model to run previously, but then added in the final replicate’s data (with more zeroes) today, it produced the following error:

Warning in fitTMB(TMBStruc) :
Model convergence problem; non-positive-definite Hessian matrix. See vignette(‘troubleshooting’)
Warning in fitTMB(TMBStruc) :
Model convergence problem; function evaluation limit reached without convergence (9). See vignette(‘troubleshooting’)

histogram of audps

I’ve tried to change the optimizer and fiddled with using a zero-inflated family, but no luck in getting the Hessian issue resolved/getting the model to converge. I’ve also attempted to run the model using a Gamma family, but it tells me that non-positive values aren’t allowed (which I have a hunch is because of the zeroes). I have attached a picture of the histogram of audps, for reference. Any help would be much appreciated!