Hans van Ophem, "The Frequency of Visiting a Doctor: Is the Decision to 
Go Independent of the Frequency?", Journal of Applied Econometrics, Vol. 
26, No. 5, 2011, pp. 872-879.

Data: The data used in the paper are from the paper

  Rainer Winkelmann, "Health Care Reform and the Number of Doctor Visits --
  An Econometric Analysis", Journal of Applied Econometrics, Vol. 19, No. 4,
  2004, pp. 455-472.

They may be found in the JAE Data Archive at

  http://www.econ.queensu.ca/jae/datasets/winkelmann001/
  
This directory simply contains two programs in the R programming 
language. They are zipped in the file hvo-progs.zip. Both files are DOS 
files in ASCII format. Unix/Linux users should use "unzip -a".

  Estimation results Table 1: prog1.r
  Estimation results Table 2: prog2.r