Abstract: This paper extended the ZTP regression model to Zero-truncated generalized Poisson regression model. An algorithm for estimating parameters was obtained and two score tests were presented for testing the ZTP regression model against the ZTGP regression model, and for testing the significance of regression coefficients. A numerical example was given to illustrate our method and the power of score tests was investigated by Monte Carlo simulation.

Key words: zero-truncated, score test, generalized Poisson regression, zero-truncated, score test