Dear all,

I have been fitting a rather large multi-state model with 5 states and one of the issues is the number of the parameters of the model. To reduce the number of parameters, instead of fitting a categorical variable of "time", I would like to instead fit a trend ("Time"). I would like the trend to vary by stratum, hence it is an interaction model of stratum:Time, however I model two seasons (summer/winter) hence it is actually stratum:season:Time.

A model specification of formula = ~stratum:season:Time works fine, but upon further reading I understand I should remove the intercept so that each parameter is independently estimated. However, a model specification of formula = -1 + stratum:season:Time returns the error of

"One or more formulae are invalid because the design matrix has all zero rows"

I receive the same error when attempting to fit this for transitions (with stratum:tostratum:season:Time)

I inspected the design matrix using the function model.matrix with the above formula specification, and indeed, the error relates to the first "Time" step of each stratum, when the value of Time is 0.0. Is this normal behaviour? As a temporary fix, I have created a variable called Time2 which is simply Time + 0.5, which is currently running but I'm not sure if this is the proper fix.

I would appreciate any advice. I am running RMark 2.2.2 on R3.4.1, and have also tried RMark 2.2.5 on R3.5.1.