Hi Jang, if you look at 'model' in Setup tab you will see the code is annotated.
and the online help describes more about this code;
https://onlinehelp.c...peParamMinusOne
gamma distribution is not the same as Weibull, see here;
https://en.wikipedia...ma_distributionhttps://en.wikipedia...ll_distribution
# ===============================================================================
/*
Assumptions on the model
- One compartment model with 1st-order clearance
- The delay time between the administration time of the drug
and the time when the drug molecules reach the central compartment
is assumed to be gamma distributed with mean = MeanDelayTime and
shape parameter being (ShapeParamMinusOne + 1)
*/
# ================================================================================
# central compartment
delayInfCpt(A1, MeanDelayTime, ShapeParamMinusOne, out = - Cl * C, dist = Gamma)
dosepoint(A1)
# drug concentration at the central compartment
C = A1 / V
# ============== residual error model ===================================================
error(CEps = 0.1)
observe(CObs = C * (1 + CEps))
# ============== Model parameters =========================================================
# ------------ structural model parameters ---------------------------------------------
stparm(V = exp(tvlogV + nlogV)) # volume of distribution for central compartment
stparm(Cl = exp(tvlogCl + nlogCl)) # central clearance
stparm(MeanDelayTime = exp(tvlogMeanDelayTime + nlogMeanDelayTime)) # mean delay time
stparm(ShapeParamMinusOne = exp(tvlogShapeParamMinusOne)) # (ShapeParameter - 1)
Edited by Simon Davis, 14 July 2020 - 09:44 AM.
added Gamma shape reference