I used the grofit package in R to fit the Gompertz growth model to my data (growth of quails over the course of several weeks). I obtained results for the three separate parameters: A, mu, and lambda. My main question is: is it possible to have negative values for lambda (lag phase)? It seems a bit strange to me, but when I fit my data to the model it gave an "ok" for the fit... so I assumed it was correct, but I cant find much of anything in the literature about the lag phase interpretation (especially if they have negative values, or if negative values are even possible and/or biologically relevant). Any help or insight would be greatly appreciated. Thank you.