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Monte Carlo Simulation

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Monte Carlo Simulation

Shane Phillips
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

______________________________________________
[hidden email] 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.
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Re: Monte Carlo Simulation

Charles Annis, P.E.
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.

[hidden email]
561-352-9699
http://www.StatisticalEngineering.com


-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On
Behalf Of Shane Phillips
Sent: Friday, April 15, 2011 2:50 PM
To: [hidden email]
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

______________________________________________
[hidden email] 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.

______________________________________________
[hidden email] 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.
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Re: Monte Carlo Simulation

Shane Phillips
Here's a script of what I have so far.  I have a few problems.  First, the correlations.  Next, recoding that categorical variable into dichotomous variables.  Finally, the iterative filename thing.

Thanks!

S

-----Original Message-----
From: Charles Annis, P.E. [mailto:[hidden email]]
Sent: Friday, April 15, 2011 3:01 PM
To: Shane Phillips; [hidden email]
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.

[hidden email]
561-352-9699
http://www.StatisticalEngineering.com


-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On
Behalf Of Shane Phillips
Sent: Friday, April 15, 2011 2:50 PM
To: [hidden email]
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

______________________________________________
[hidden email] 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.

______________________________________________
[hidden email] 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.
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Re: Monte Carlo Simulation

Ista Zahn-2
In reply to this post by Shane Phillips
Hi Shane,
See ?rbinom, ?rnorm, ?mvrnorm (in the MASS package), ?sample, ?for and
?write.table

Best,
Ista

On Fri, Apr 15, 2011 at 2:49 PM, Shane Phillips
<[hidden email]> wrote:

> 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
>
> ______________________________________________
> [hidden email] 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.
>



--
Ista Zahn
Graduate student
University of Rochester
Department of Clinical and Social Psychology
http://yourpsyche.org

______________________________________________
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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.
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Re: Monte Carlo Simulation

Jeremy Miles-2
In reply to this post by Shane Phillips
On 15 April 2011 12:03, Shane Phillips <[hidden email]> wrote:
> Here's a script of what I have so far.  I have a few problems.  First, the correlations.  Next, recoding that categorical variable into dichotomous variables.  Finally, the iterative filename thing.
>

 Where?

Perhaps give the list one question at a time?

Here's a start for one of the questions, selected (almost) at random.
Give 80% of people a score of 1 on a x1, and 20% of people zero.

tempVar <- runif(1000)
x1 <- ifelse(tempVar < 0.8, 1, 0)
rm(tempVar)


Tell us how far you've got.  Do you need to know about write.table()
for the saving the files, or is the problem with splitting a large
file, or generating the 1000 names ...


Jeremy



--
Jeremy Miles
Psychology Research Methods Wiki: www.researchmethodsinpsychology.com

______________________________________________
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https://stat.ethz.ch/mailman/listinfo/r-help
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and provide commented, minimal, self-contained, reproducible code.
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Re: Monte Carlo Simulation

Shane Phillips
In reply to this post by Charles Annis, P.E.
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. [[hidden email]]
Sent: Friday, April 15, 2011 3:00 PM
To: Shane Phillips; [hidden email]
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.

[hidden email]
561-352-9699
http://www.StatisticalEngineering.com


-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On
Behalf Of Shane Phillips
Sent: Friday, April 15, 2011 2:50 PM
To: [hidden email]
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

______________________________________________
[hidden email] 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.
______________________________________________
[hidden email] 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.
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Re: Monte Carlo Simulation

MacQueen, Don
In reply to this post by Jeremy Miles-2
See below:

--
Don MacQueen

Lawrence Livermore National Laboratory
7000 East Ave., L-627
Livermore, CA 94550
925-423-1062





-----Original Message-----
From: Jeremy Miles <[hidden email]>
Date: Fri, 15 Apr 2011 14:17:13 -0700
To: Shane Phillips <[hidden email]>
Cc: "[hidden email]" <[hidden email]>
Subject: Re: [R] Monte Carlo Simulation

>On 15 April 2011 12:03, Shane Phillips <[hidden email]> wrote:
>> Here's a script of what I have so far.  I have a few problems.  First,
>>the correlations.  Next, recoding that categorical variable into
>>dichotomous variables.  Finally, the iterative filename thing.
>>
>
> Where?
>
>Perhaps give the list one question at a time?
>
>Here's a start for one of the questions, selected (almost) at random.
>Give 80% of people a score of 1 on a x1, and 20% of people zero.
>
>tempVar <- runif(1000)
>x1 <- ifelse(tempVar < 0.8, 1, 0)
>rm(tempVar)

x1 <- rbinom(1000,1,0.8)

>
>
>Tell us how far you've got.  Do you need to know about write.table()
>for the saving the files, or is the problem with splitting a large
>file, or generating the 1000 names ...
>
>
>Jeremy
>
>
>
>--
>Jeremy Miles
>Psychology Research Methods Wiki: www.researchmethodsinpsychology.com
>
>______________________________________________
>[hidden email] 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.

______________________________________________
[hidden email] 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.
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Re: Monte Carlo Simulation

MacQueen, Don
In reply to this post by Shane Phillips
The filenames can be done within a loop, like this:

for (id in 1:1000) {
  ## the filename
  fname <- paste('sample', formatC(id,width=4,flag='0'),'.tsv',sep='')

   ## more stuff
}


-Don

--
Don MacQueen

Lawrence Livermore National Laboratory
7000 East Ave., L-627
Livermore, CA 94550
925-423-1062





-----Original Message-----
From: Shane Phillips <[hidden email]>
Date: Fri, 15 Apr 2011 11:49:48 -0700
To: "[hidden email]" <[hidden email]>
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
>
>______________________________________________
>[hidden email] 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.

______________________________________________
[hidden email] 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.
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