search for: nasdc

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: I am having difficulties with the fitted values at different levels of a multilevel model. My data set is a series of student test scores over time with a total of 7,280 observations, 1,720 students nested witin 60 schools. The data set is not balanced. The model was fit using eg.model.1<-lme(math~year, random=~year|schoolid/childid, data=single). When I call the random

I am learning about sparse matrices and wonder if R can create them from a full matrix. Can anyone tell me how I might be able to accomplish this. ------ Harold C. Doran Director of Research and Evaluation New American Schools 675 N. Washington Street, Suite 220 Alexandria, Virginia 22314 703.647.1628 <http://www.edperform.net/> [[alternate HTML version deleted]]

Dear List I have math test scores for male and female students where gender is a dummy code (female =1). I also have a variety of other demographic variables. However to begin, I want to create a very simple stripchart where female math scores are a blue circle and male scores are a red triangle. I am having difficulty using conditional statements to accomplish this. Thank you. ------

Dear List: I have a data set with over 7000 students with about 4 observations over time per student. I want to examine the within-group fits of a random sample of this group as it takes forever to compute and draw all 7000 regressions. Here is the code I have used so far. >group<-groupedData(math~year|childid, data=scores) >group.list<-lmList(group)

Dear list In HLM, one can specify a covariate at one of the "levels". For example, if the data structure are repeated observations nested within students nested within schools, school size might be a covariate that is used at level 3, but not at the other levels. In HLM this is rather easy to do. However, how can one specify a covariate in R for only one of the levels? I have a

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

...4395 Fax (+44) 020 7679 7096 f.calboli at ucl.ac.uk ------------------------------ Message: 19 Date: Thu, 26 Jun 2003 10:54:50 -0400 (EDT) From: "J.R. Lockwood" <lockwood at rand.org> Subject: RE: [R] within group variance of the coeficients in LME To: Harold Doran <hdoran at nasdc.org> Cc: R-Help <r-help at stat.math.ethz.ch>, Andrej Kveder <andrejk at zrc-sazu.si> Message-ID: <Pine.LNX.4.33.0306261037560.6707-100000 at penguin.rand.org> Content-Type: TEXT/PLAIN; charset=US-ASCII > > Dear listers, > > I can't find the variance or s...

I am trying to import a file using R Commander. It was working a few days ago, but now I get the following message when I try to import from SPSS. Any thoughts? Error in parse(file, n, text, prompt) : parse error ------ Harold C. Doran Director of Research and Evaluation New American Schools 675 N. Washington Street, Suite 220 Alexandria, Virginia 22314 703.647.1628

I have loaded the foreign package and am still having problems with an import. I get a message that reads, unable to open file. Whe I try different files I get the same message. Here is the code I used. Am I missing something? I am using 1.7 and have also tried this in 1.6 with the same problem. hsb<-read.spss("C:\HLM504_Student\Examples\AppendxA\HSB1.SAV", use.value.labels=TRUE,

Hello R-Helpers, I was trying to use the lmList function to get the lmList graphic similar to Pinheiro and Bates (pg 33). I did not have a problem creating the graphic when I used the Orthodont data frame or 2 other data sets when there are no missing values. My data has missing values. Do I need to remove the missing values before the lmList function will work? for a small example: > a

Dear R: I am trying to fit a doubly multivariate LME (DM) where I have two response variables measured on two occasions per person. Specifically, reading and math scores measured at the beginning and ending of a school year. The response variables have a correlation of r = .85. The response variables in the data matrix are stacked in a vector with a dummy code flagging each outcome and with

Dear List: I am trying to figure out how to incorporate measurement error in an longitudinal educational data set using lme to create a "true score" model. As a by-product of the procedures used to scale educational tests, one can obtain a person-specific measurement error associated with each score, or a conditional standard error. For example, a score of 200 would have measurement

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 unsure if my problem is with Sweave or LaTeX. Anyhow, I am using the MikTeX distribution and TexnicCenter. I can easily create Sweave files and all goes well until I try to incorporate graphics. I use the same code as found in the examples found in the users manual. In R, the graphics I want are created as Sweave is creating the .tex file. When I examine the .tex file

Dear List: Earlier this week I posted a question and received no response, and I continue to struggle with my model. My original question is pasted below. I am using lme and want to fix the variance of the within group residual at 1 (e~n(0,1). I think the varFixed function should be used to accomplish this, but I am struggling to figure out how to do this. Can anyone offer suggestions on how