Re: DV Simulation

From: Nick Holford Subject:Re: [NMusers] DV Simulation Date: Fri, 30 May 2003 07:58:31 +1200 Jing, I have never noticed this option before. I have also done simulations of odd-type data in collaboration with Stuart Beal and he did not suggest using it. NMHELP says this: PREDICTION | Permitted with ONLYSIM, but is not required. Indicates that Y | (with NM-TRAN abbreviated code) or F (with a user-supplied PRED | or ERROR routine) will be set to a simulated value. Also, etas | (if any) are population etas only if epsilons also appear. This | is the default. | NOPREDICTION | Permitted with ONLYSIM, but is not required. Indicates that the | DV data item will be set directly to the simulated value in | abbreviated or user-supplied code (as when simulating odd-type | data). Also, etas (if any) are always population etas, even if | epsilons do not appear. This "help" is a mystery to me. PREDICTION refers to what happens to Y and F while NOPREDICTION refers to what happens to DV. Can anyone help translate this into something of practical use? NMHELP says this about FORWARD: NOFORWARD | When a table file is opened during a given problem, it is posi- | tioned at the start of the file. This is the default. | FORWARD | When a table file is opened during a given problem, it is for- | warded to the end of the file. | This is another option I have never used. It refers to the behaviour if you have more than one $PROBLEM in your control stream and you use the same FILE in $TABLE in different problems. This means that output from each problem will be added to the end of the output from previous problems in the same table file. Note that a problem is not the same as a $SIMULATION SUBPROBLEM. In $SIMULATION the output from each subproblem is automatically appended to the table file. FORWARD (on the first $TABLE record) caused output to be appended to the first table file I had created with a previous run of the control stream (note only one $PROBLEM in the control stream). The second table file in my control stream was overwritten when I re-ran the problem. To have output appended to the second table file I had to specify the FORWARD option explicitly for that file. So based on my testing I would have to disagree with Tom's suggestion that FORWARD applied to the first $TABLE record becomes the default for subsequent tables. The observed behaviour is more flexible and therefore IMHO preferable. Nick -- Nick Holford, Dept Pharmacology & Clinical Pharmacology University of Auckland, 85 Park Rd, Private Bag 92019, Auckland, New Zealand email:n.holford@auckland.ac.nz tel:+64(9)373-7599x86730 fax:373-7556 http://www.health.auckland.ac.nz/pharmacology/staff/nholford/