similar to: average by group...

Dear List: When I click on the link to download a reference manual for a package on cran, I get an error message that the file is damaged and could not be repaired. I randomly chose various packages and the same error message appears. Are the links actually broken? I have also restarted my machine and closed and re-opened acrobat. I am using Windows XP, Acrobat Professional 6.0.0.5, and

Hello everyone. I would like to find the sample covariance matrix using R. So far I read on the wikipedia what a sample_covariance is http://en.wikipedia.org/wiki/Sample_covariance according to wikipedia one vector is enough to calculate the sample covariance matrix. In R I tried cov(myvector) and I get the reply that I need to pass either two argument or one matrix with x,y values . How can I

I'm attempting to build an R package for distribution and am working from the directions found at http://www.maths.bris.ac.uk/~maman/computerstuff/Rhelp/Rpackages.html#Wi n-Win I've read through Writing R Extensions and various other "helpful" web sites. I've installed all relevant software (perl, cygwin, mingwin, hhc.exe). Here is what I have done so far: 1) Sourced data

I need to wrap a loop inside a function and am having a small bit of difficulty getting the results I need. Below is a replicable example. # define functions pcm <- function(theta,d,score){ exp(rowSums(outer(theta,d[1:score],'-')))/ apply(exp(apply(outer(theta,d, '-'), 1, cumsum)), 2, sum) } foo <- function(theta,items, score){ like.mat <-

Dear List: I have searched the archives and my R books and cannot find a method to transform a continuous variable into a binary variable. For example, I have test score data along a continuous scale. I want to create a new variable in my dataset that is 1=above a cutpoint (or passed the test) and 0=otherwise. My instinct tells me that this will require a combination of the transform

I am new to R and would like to get some practice analyzing multilevel data. I wonder if anyone can point me to a sample data set and command lines that I might replicate for a sample session. I would then compare my output with HLM output. Any help is appreciated. ------ Harold C. Doran Director of Research and Evaluation New American Schools 675 N. Washington Street, Suite 220 Alexandria,

Dear List: I am working to construct a matrix of a particular form. For the most part, developing the matrix is simple and is built as follows: vl.mat<-matrix(c(0,0,0,0,0,64,0,0,0,0,64,0,0,0,0,64),nc=4) Now to expand this matrix to be block-diagonal, I do the following: sample.size <- 100 # number of individual students I<- diag(sample.size) bd.mat<-kronecker(I,vl.mat) This

Dear List: I am trying to find the area between two ECDFs. I am examining the gap in performance between two groups, males and females on a student achievement test in math, which is a continuous metric. I start by creating a subset of the dataframe male<-subset(datafile, female="Male") female<-subset(datafile, female="Female") I then plot the two CDFs via

Dear List: When trying to open 1.9.0 this morning, I have the following error: "Fatal Error: Unable to restore saved data in .Rdata" I am using Windows 2000. The program then quits. Do I need to reinstall? Harold C. Doran One Massachusetts Avenue, NW · Suite 700 Washington, DC 20001-1431 202.336.7075 [[alternative HTML version deleted]]

Dear List: I am generating a series of plots iteratively using Sweave. In short, a dataframe is subsetted row by row and variable graphics are created conditional on the data in each row. In this particular case, this code ends up generating 17,000 individual plots. In some cases, all student data (this is working with student achievement data) are available and my code below works very well in

Dear List: I have a question regarding an MDS procedure that I am accustomed to using. I have searched around the archives a bit and the help doc and still need a little assistance. The package isoMDS is what I need to perform the non-metric scaling, but I am working with similarity matrices, not dissimilarities. The question may end up being resolved simply. Here is a bit of substantive

Martin In terms of context of the actual problem, sapply is called millions of times because the work involves scoring individual students who took a test. A score for student A is generated and then student B and such and there are millions of students. The psychometric process of scoring students is complex and our code makes use of sapply many times for each student. The toy example used

It sounds as thought you are interested in Hoyt's Anova which is a form of generalizability theory. This is usually estimated using by getting the variance components from ANOVA. > -----Original Message----- > From: r-help-bounces at stat.math.ethz.ch > [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Karl Knoblick > Sent: Tuesday, May 16, 2006 6:10 AM > To: r-help at

Dear List I apologize for the multiple postings. After being in the weeds on this problem for a while I think my original post may have been a little cryptic. I think I can be clearer. Essentially, I need the following a <- c(2,3) b <- c(4,5,6) (2*4) + (2*5) + (2*6) + (3*4) + (3*5) +(3*6) But I do not know of a built in function that would do this. Any suggestions? -----Original

Dear List: I am encountering an error that I can't resolve. I'm looping through rows of a dataframe to generate individual tex files using Sweave. At random points along the way, I encounter the following error Error in file() : cannot find unused tempfile name At which point Sweave halts. There isn't a logical pattern that I can identify in terms of why the program stops at

I'm trying to read in some data from a .csv format and have come across the following issue. Here is a simple example for replication # A sample .csv format schid,sch_name 331-802-7081,School One 464-551-7357,School Two 388-517-7627,School Three \& Four 388-517-4394,School Five Note the third line includes the \ character. However, when I read the data in I get >

Dear R: Am I having trouble downloading the LME4 library. I am using Windows and am using ver 1.7 I have tried the following: 1) Install package from CRAN, but LME4 is not listed 2) Downloaded LME4 from http://cran.us.r-project.org/, however, I cannot open the file when I try install from local drive. I get the following error: Error in file(file, "r") : unable to open connection

Dear list Suppose I have the following vector: x <- c(3,4,2,5,6) Obviously, this sums to 20. Now, I want to have a second vector, call it x2, that sums to x where 5 <= x <= 20, but there are constraints. 1) The new vector must be same length as x 2) No element of the new vector can be 0 3) Element x2[i] of the new vector cannot be larger than element x[i] of the original vector 4)

This is just posed out of curiosity, (not as a criticism per se). But what is the functional role of the argument na.rm inside the mean() function? If there are missing values, mean() will always return an NA as in the example below. But, is there ever a purpose in computing a mean only to receive NA as a result? In 10 years of using R, I have always used mean() in order to get a result, which is

Hi all: I'm having difficulty with something I believe is very simple, but I'm stuck. I have a large data frame that took days to clean and prepare. All I now need to do is concatenate three variables into a single column. For example, I have tenn$up, tenn$down, and tenn$stable which all have values of 1 or 0. I simply want to put all three columns together to create a pattern (e.g.,