Error: Hessian is singular. Try providing starting values or using fewer covariates

[ABCD]

I am trying to fit the occupancy model for Barking deer. When I tried to fit the occupancy model in R using "occu" function, it prints the 

Error: Hessian is singular.  Try providing starting values or using fewer covariates. 

I went through replies in the group but could not find how to determine the start value? I tried providing some starting value. Later it asked 16 start value. And I gave 16 start value but it didn't work. I could not get what could be the appropriate value of starting point? Hope to get solution for this!

[Jeffrey Royle]

I suggest starting with simpler models (a few parameters, not 16) and then adding a parameter  at a time to find out exactly which additional parameter is causing the failure.

16 parameters Is a lot, so unless you have an enormous data set it may not be possible to fit such a model.  In any case, stepwise building up of the model and using the estimates of each previous model as starting values will often solve the problem.

The order of the starting values will be exactly the order that the parameters are printed, which you can diagnose by running a simpler occupancy model and inspecting the output.

regards

andy

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