... Each one of these studies collected data on the number of poultry kept by the sampled households in the study year and, in the case of Kenya, Nigeria, and Ghana, on the number of poultry sold and ... either the logistic function or the standard normal cumulative distribution function (the probit function) (Greene 1997b). The mean and variance of the ZINB are (18) , To test whether the ... (Scenario 4) and supply shocks (all other scenarios), as well as the impact of the supply shocks on poultry keepers of different scales. The duration of the livelihoods impacts of these shocks...