HPC: Stata module to perform specification test to discriminate between models for non-negative data with many zeros

hpc computes the HPC test (Santos Silva, Tenreyro, and Windmeijer, Journal of Econometric Methods, 2015) for the case where the conditional expectation of a nonnegative variable is specified as the product of the exponential of a linear combination of regressors, times a function of the regressors that is bounded between zero and one (and can be identically equal to one). Examples of such models are given in Table 1 of Santos Silva, Tenreyro, and Windmeijer (2015). Other models that satisfy this condition are the Poisson and negative-binomial models and their zero inflated counterparts.