a measure of health status (larger positive numbers are associated with poorer health)
Source
Gurmu, Shiferaw (1997) “Semiparametric estimation of hurdle regression models with an application to medicaid utilization”, Journal of Applied Econometrics, 12(3), 225-242.
References
Davidson, R. and James G. MacKinnon (2004) Econometric Theory and Methods, New York, Oxford University Press, http://www.econ.queensu.ca/ETM/, chapter 11.