On Tue, Nov 18, 2008 at 3:41 AM, gauravbhatti <[EMAIL PROTECTED]> wrote: > > Hi all can any one of you write a script for the following problem
Well, yes, but that sounds remarkably like a homework problem, and we can't and won't do your school assignments for you. Your instructor gave you some suggestions on where to start; you can use RSiteSearch or Google to find more information. Beyond that, someone here may be inclined to assist if you run into a specific problem, but really, that's what your instructor is paid to do. Sarah > Let X be a matrix of random normal values (mean =0; sd=1) (see rnorm() > function) having 10 columns and N=100 rows. Let the first row in the matrix > be (1,1.5,1.4,3,1.9,4,4.9,2.6,3.2,2.4). Assume that the first 5 columns of > data for each row correspond to a group A, while the remaining 5 to another > group B. > > For each row of the matrix X, compute: > a) the t-statistic comparing the groups A and B assuming equal variance > b) Compute the probability to observe such a t-statistics only by chance, > using a permutation analysis. The following strategy will be used: the > columns will be randomly permuted nk=100 times, and at each iteration the > t-statistic will be computed again and recorded in a vector. At the end, > compute the p-value as the number of times out of nk when the t-statistic > with the permuted data was at least as or more extreme than the t-statistics > obtained with the real (non-permuted data). > Present the result as a dataframe with 3 columns: ID= Row number, t= > t-score, p=p-value; > > -- -- Sarah Goslee http://www.functionaldiversity.org ______________________________________________ R-help@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.
