similar to: R help

Hi, What package would you recommend for analyzing the validity/reliability of multiple choice tests. Doing things such as classical test analysis, factor analysis, item response theory. I've used psychometric (item.exam), MiscPsycho (alpha.Summary), and ltm (rcor.test). MiscPsycho reported the numbers most similar to what I get in SPSS: corrected point biserial correlations,

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Hello, I am trying to do a logistic regression and have one predictor variable (x) that is ratio and two predictor variables (y and z) that are categorical. These have three levels each which I have called "High", "Medium" and "Low". My question: do I need to use a numerical coding scheme for the categorical variables as required by some statistical software

Dear R Gurus, I have a problem related to plot. For example, I have two variables, pre and post. pre <- c(1,2,3,4,5) post <- c(2,5,7,2,3) How can I plot a line graph similar to this one? http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1847566&rendertype=figure&id=F1 Would you please provide me a keyword so that I can search. I don't know what is the name of this

Dear R helpers, I have a question regarding wordpress and R. I have asked this question in Wordpress support ( http://wordpress.org/support/topic/368312 ) but there is no answer so far, maybe the R community can have a better answer. I followed the excellent tutorial on r-statistics-blog ( http://www.r-statistics.com/2010/02/r-syntax-highlight-on-your-blog-a-wordpress-plugin/ ) to enable syntax

Dear R experts, I have plot the PDF of t distribution with df = 74. curve(dt(x,df=74),from=-4, to=4) how can I shade the area under curve (for example, col="red") from t=+- 1.996? Thank you. Regards, CH -- CH Chan Research Assistant - KWH http://www.macgrass.com

Hi everybody, somehow i dont get the shapiro wilk test for normality. i just can?t find what the H0 is . i tried : shapiro.test(rnorm(5000)) Shapiro-Wilk normality test data: rnorm(5000) W = 0.9997, p-value = 0.6205 If normality is the H0, the test says it?s probably not normal, doesn ?t it ? 5000 is the biggest n allowed by the test... are there any other test ? ( i know qqnorm

Hi All, I'm fitting a Poisson regression. And I want to plot 95% Confidence Interval of Regression Estimates. After coming back to original scale (using following formula): exponential(estimate +/- 1.96*SE), at best I can get the output in the form of estimates, lower_limit, upper_limit values. As far I know forest() in metafor package needs input in the form of estimates and their

Hi, i have a question in R, How and what command you need to do to run a kruskal-wallis test without the built in command 'kruskal.test'? many thanks. _________________________________________________________________ [[alternative HTML version deleted]]

Hi everyone, I am trying to install R-2.6 over my 2.5.1 installation on Mac OS X 10.5. R version 2.5.1 (2007-06-27) I double-click the installer package, 1) Click Continue 2) Click Continue 3) Click Continue + Click Agree On the "Installation Type" dialog screen, all four options are grayed out, with skip beside them. The Install button is also grayed out. If I click the

Hi there, I've used R before, but I just got a new computer with Leopard and I'm having trouble installing. I download the installer, but when I reach the end of the install process, the "install" button remains gray and unclickable. I've tried both standard and custom, as well as installing on my flash disk, to no avail. Any suggestions? I'd rather not build from

Dear Sir Sir when I use "png" function to save graph. At last it is written dev.off(). it does not produce any postscript file. Please help in this regard Thank you -- AMINA SHAHZADI Department of Statistics GC University Lahore, Pakistan. [[alternative HTML version deleted]]

I've spent several hours trying to track the answer down myself and failed miserably so a simple question for everyone that will no doubt have a painfully obvious answer. What's the command to calculate the critical value of r using a two tailed test with a given alpha and degrees of freedom? I.e., alpha=0.05, df=18, two-tailed test, with the result being 0.4438 -- View this message in

Dear R People: Is there a Quality Control in R book that would be accessible for undergraduates, please? I'm teaching a QC course in the fall semester and would be happy to have a Use R book or something like that, please. Thanks in advance, Erin -- Erin Hodgess Associate Professor Department of Computer and Mathematical Sciences University of Houston - Downtown mailto: erinm.hodgess at

Hello, I would like to find out how to use R to compute the effect size of two samples for a two sample t test. Is there a formula for the fisher's exact test? Any R code and/or formula would be greatly appreciated. Thanks, Jim [[alternative HTML version deleted]]

Hi, I am wondering if there is a package for doing conditional logistic regression for nested case-control study as described in "Estimation of absolute risk from nested case-control data" by Langholz and Borgan (1997) where Horvitz-Thompson sampling weight (log of (number in the risk set divided by the number sampled)) is used with regression. In SAS Proc Phreg, this is implemented

hie 1...i'm trying to carryout a relibility testusing cronbach's alpha what fuctin do i use. 2.. this is more of a statistical question.if the alpha value for all the variables is negative what does it mean. and if the alpha value is negative for all tyha variables but is greater than 0.7 for some sections of the variables what does that mean thanks in advance

Hi, why don't you try try ks.test(VeriSeti1, VeriSeti2)$p.value All the best Jenny >How can i print only the P-Value of the kolmogorov smirnov test? > > >> ks.test(VeriSeti1, VeriSeti2) > > Two-sample Kolmogorov-Smirnov test > >data: VeriSeti1 and VeriSeti2 >D = 0.5, p-value = 0.4413 >alternative hypothesis: two-sided > > >This expression

Dear R-Help, I'm hoping to find a Multinomial Nested Logit package in R. It would be great to find something analogous to "PROC MDC" in SAS: > The MDC (Multinomial Discrete Choice) procedure analyzes models > where the > choice set consists of multiple alternatives. This procedure > supports conditional logit, > mixed logit, heteroscedastic extreme value,

Hello all, I have a question concerning how to get the P-value for a explanatory variables based on GLM. I'll run multiple regressions with GLM, and I'll need the P-value for the same explanatory variable from these multiple GLM results. I check the help and there are quite a few Value options but I just can not find anyone about the p-value. Could anyone help me with that?