To whom it may concern: Given that my sample size is n, my mean is 100, and my sd is 10, I need to use a random number generator (which I believe is the function rnorm(5,100,10)), but I need to repeat it a large number of times, and then plot the sampling distributions of the sample means, sd's, and variances of those generated sets. I'm having a real hard time trying to figure out how to do this easily. Please help if possible! Thanks, Cheryl
Student Exercise?! Cheryl H. wrote:> To whom it may concern: > Given that my sample size is n, my mean is 100, and my sd is 10, I need > to use a random number generator (which I believe is the function > rnorm(5,100,10)), but I need to repeat it a large number of times, and > then plot the sampling distributions of the sample means, sd's, and > variances of those generated sets. I'm having a real hard time trying to > figure out how to do this easily. Please help if possible! Thanks, > Cheryl > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help >-- Dr Murray Jorgensen http://www.stats.waikato.ac.nz/Staff/maj.html Department of Statistics, University of Waikato, Hamilton, New Zealand Email: maj at waikato.ac.nz Fax 7 838 4155 Phone +64 7 838 4773 wk +64 7 849 6486 home Mobile 021 1395 862
Yes it looks like a really good student exercise into the sampling properties of a distribution. What you need to do is initialize vectors beforehand that will contain the mean and variance values. Then simply use a for() loop that generates 5 random numbers. Use the mean(), var() and store the values into the vector. Then a simple plot() should suffice. Since it is a simple problem, I will leave you to it. -----Original Message----- From: Murray Jorgensen [mailto:maj at stats.waikato.ac.nz] Sent: Wednesday, March 19, 2003 12:39 PM Cc: R-help at stat.math.ethz.ch Subject: Re: [R] r-help using random generating Student Exercise?! Cheryl H. wrote:> To whom it may concern: > Given that my sample size is n, my mean is 100, and my sd is 10, I > need > to use a random number generator (which I believe is the function > rnorm(5,100,10)), but I need to repeat it a large number of times, and> then plot the sampling distributions of the sample means, sd's, and > variances of those generated sets. I'm having a real hard time tryingto> figure out how to do this easily. Please help if possible! Thanks, > Cheryl > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help >-- Dr Murray Jorgensen http://www.stats.waikato.ac.nz/Staff/maj.html Department of Statistics, University of Waikato, Hamilton, New Zealand Email: maj at waikato.ac.nz Fax 7 838 4155 Phone +64 7 838 4773 wk +64 7 849 6486 home Mobile 021 1395 862 ______________________________________________ R-help at stat.math.ethz.ch mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
You can save some time by generating all your samples at one time: t1 <- matrix(rnorm(5 * n, 100, 10), nc = n) apply(t1, 2, mean) (Or use colVars and colMeans to save even more time) Hope this helps, Matt Wiener -----Original Message----- From: Cheryl H. [mailto:cherylh at montana.edu] Sent: Tuesday, March 18, 2003 11:26 PM To: R-help at stat.math.ethz.ch Subject: [R] r-help using random generating To whom it may concern: Given that my sample size is n, my mean is 100, and my sd is 10, I need to use a random number generator (which I believe is the function rnorm(5,100,10)), but I need to repeat it a large number of times, and then plot the sampling distributions of the sample means, sd's, and variances of those generated sets. I'm having a real hard time trying to figure out how to do this easily. Please help if possible! Thanks, Cheryl ______________________________________________ R-help at stat.math.ethz.ch mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help ------------------------------------------------------------------------------