Monte Carlo Simulation
I apologize for my last post. here is the script I forgot to paste! subject=1:1000 treat=rbinom(1*1000,1,.13) gender=rbinom(1*1000,1,.5) eth=runif(1*1000, min=1, max=4) cogat=rnorm(1*1000, 100, 16) map=rnorm(1*1000, 200, 9) growth=0 simtest=data.frame (subject=subject, treat=treat, gender=gender, eth=round(eth,digits=0), cogat=round(cogat,digits=0),map=round(map,digits=0),growth) simtest<-transform(simtest, growth=rnorm(1000,m=ifelse(treat==0,0.1,0.5),s=0.03)) simtest Once again the issues are the correlations, the recoding of the categorical variable and the iterations. Thanks to all who have helped so far! You are all so smart! S
From: Charles Annis, P.E. [charles.annis at statisticalengineering.com]
Sent: Friday, April 15, 2011 3:00 PM
To: Shane Phillips; r-help at r-project.org
Subject: RE: [R] Monte Carlo Simulation
Sent: Friday, April 15, 2011 3:00 PM
To: Shane Phillips; r-help at r-project.org
Subject: RE: [R] Monte Carlo Simulation
What have you tried so far? It is often helpful to begin with a much simpler problem, then add complexity incrementally until you've constructed the desired model. Best wishes. Charles Annis, P.E. Charles.Annis at StatisticalEngineering.com 561-352-9699 http://www.StatisticalEngineering.com -----Original Message----- From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Shane Phillips Sent: Friday, April 15, 2011 2:50 PM To: r-help at r-project.org Subject: [R] Monte Carlo Simulation Hello, R friends... I am very new to R, and I need some help. I am trying to construct a simulation for my dissertation. I need to create 1000 datasets of 1000 subjects with the following variables... Treatment variable - Drawn from a binomial distribution (1 run, prob=.13) Covariate 1 - Drawn from a normal distribution (mean=100, sd=16) Covariate 2 - Drawn from a normal distribution (mean=200, sd=9) Covariates 1 and 2 need to be correlated (say, r=.80) Covariate 3 - Drawn from a binomial distribution (1 run, prob=.5) Covariate 4 - Drawn from a distribution of discrete variables where 1 has an 80% chance of being selected, 2 - 10%, 3 - 5% and 4 - 5%. This variable would need to be recoded into 4 binary variables. Covariate 5 - Drawn from a normal distribution (mean=84, sd=2) Covariate 6 - Drawn from a binomial distribution (1 run, prob=.15) Covariate 6 needs to correlate with Covariate 2 (r=.70, or so) I need each dataset saved as a new datafile with an iterative filename (e.g. sample1, sample2, etc.). Please help! Thanks! Shane ______________________________________________ R-help at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.