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I'm trying to create a simulation of drug concentration based on the dose of a drug given. I have some preliminary data and I used a random effects model to analyze the relationship between log(dose), predicting log(drug concentration), modelling subject as a random effect.

The results of that analysis are below. I want to take these results and simulate similar data in SAS, so I can look at the effect of changing doses on the resulting concentration of drug in the body. I know that when I simulate the data, I need to ensure the random slope is correlated with the random intercept, but I'm unsure exactly how to do that. Any example code would be appreciated.

Random effects:

Formula: ~LDOS | RANDID
Structure: General positive-definite, Log-Cholesky parametrization
StdDev Corr
(Intercept) 0.15915378 (Intr)
LDOS 0.01783609 0.735
Residual 0.05790635

Fixed effects: 

LCMX ~ LDOS
Value Std.Error DF t-value p-value
(Intercept) 3.340712 0.04319325 16 77.34339 0
LDOS 1.000386 0.01034409 11 96.71090 0

Correlation:

(Intr)
LDOS -0.047
Joe
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  • This question is somewhat of an edge case, but it seems to me ultimately you're not really asking a programming question, but a question for a statistician. As such I'd ask on [CrossValidated](http://stats.stackexchange.com/). – Joe Dec 23 '13 at 20:06
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    I would note that if you get answers on the statistical side of things [ie, theoretically how one uses this to do this statistically speaking], it becomes a good question for here; and it's possible that some folks here will cover both bases (as could the CV folks). I'm not voting to close for that reason - just suggesting a different source of potential answers. If you get a comprehensive answer on one or the other, then ask for the other to be closed. – Joe Dec 23 '13 at 20:16
  • I actually posted on CrossValidated and they suggested I post here. So I have it posted on both... hopefully I can get an answer in one venue or another! – Bosley Dec 23 '13 at 20:22
  • Yeah, it's sort of an edge case. Doing this requires both programming AND statistical knowledge... so it's not really perfect for either. You might also try on [communities.sas.com](http://communities.sas.com/), if you don't get a good answer here. – Joe Dec 23 '13 at 20:23
  • I'm not an expert in this, but you should be able to use PROC MCMC to simulate the fitted model. Look at the first example "Simulating Samples from a Known Distribution" in the SAS doc. – DomPazz Dec 23 '13 at 21:09

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