(GML note - see ~\d\mp\dabs_data\aki_jin\aki_init.do)
see Appendix B of reference for simulation description.
reference - Pepe M, Zheng Y, Jin Y.  Evaluating the ROC performance of   markers for future events.  UW Biostatistics Working Paper Series no. 313.    University of Washington. 2007.
simulated biomarker data for detection of acute kidney injury (AKI)   during major cardiac surgery
valid only for statusall = 1,2,9.
time from marker measurement to AKI event
marker measurement time with respect to surgery
controls = no AKI after surgery