Modeling Rates and Effects of Drug X

There is one more point you might want to mention about modelled rates in PREDPP. You can send this to nmusers, if you think it is relevant. The rate R1 computed with a given event record applies to the *preceding* time period. Suppose the subject is on drug from time 0 to time 8, and off drug from time 8 to time 24. The ONDR value must be specified as follows. (Note that ONDR value when TIME=0 is irrelevant; either 0 or 1 could be coded.) First, suppose observations were made at time 8 and 24 (x1 and x2): #ID TIME AMT RATE ONDR X=DV 1 0 9999 -1 0 . 1 8 . . 1 x1 1 24 . . 0 x2 Second, suppose there was an observation at time 4 (during the "on drug" period) and at time 24 (the end of the "off drug" period). It is necessary to use the "other" type event records (EVID) to signal the change in drug status. #ID TIME AMT RATE ONDR X=DV EVID 1 0 9999 -1 0 . 1 1 4 . . 1 x1 0 1 8 . . 1 . 2 1 24 . . 0 x2 0