ENROLLSLP	=	variable measuring difference in rate of change of utilization during enrollment relative to pre-KenPAC (coded 1,2,3…N if enrollment period; 0 if otherwise)
POSTSLP	=	variable measuring difference in rate of change of utilization during post-KenPAC relative to pre-KenPAC (coded 1,2,3…N if post-KenPAC period; 0 if otherwise)