Re: Assigning occasions to sparse data

Mike, Estimating BOV from 8 occasions or from 4 occasions will take essentially the same computation time (if you use BLOCK (*) SAME). But assuming ETA is the same on two of the occasions (which are collapsed together from having 4 occasions instead of 8) will necessarily induce model misspecification on those occasions. The "how much improvement" will depend on the size of BOV and residual error and other model related issues. But whether there is an improvement or not costs essentially nothing. Why add this problem when it can be avoided simply by using BOV on 8 occasions? Nick [EMAIL PROTECTED] wrote: > > Hi Steve; > > Yes there is no requirement that the number of occasions be the same in every > study (I have both 2 period and 4 period studies in my Phase 1 dat set). But, > from a practical stand-point, how much is too much? I guess I'd like to keep > things simple, both for practical reasons and also that I'm not completely > convinced that modeling 8 occassions (as opposed to 4) would really result in > that much of an improvement. > > Mike > -- Nick Holford, Dept Pharmacology & Clinical Pharmacology University of Auckland, 85 Park Rd, Private Bag 92019, Auckland, New Zealand [EMAIL PROTECTED] tel:+64(9)373-7599x86730 fax:+64(9)373-7090 www.health.auckland.ac.nz/pharmacology/staff/nholford