similar to: Coding of categorical variables for logistic regression?

I notice something curious about how aov() treats a numeric factor: "score" is a dependent variable and "group" is a factor in a one-way ANOVA. But "group" contains numeric codes and is not a factor (checked with is.factor). An ANOVA done using: > aov(score~factor(group), data=mydata) gives the right answers. But > aov(score~group, data=mydata) also

I have tried looking for the source code for the pt() function in https://svn.r-project.org/R/trunk/src/library/stats/ and am unable to find it there. Can someone please tell me where to find it? Thanks, Ravi Kulkarni -- View this message in context: http://n4.nabble.com/Source-code-for-the-t-distribution-tp1585875p1585875.html Sent from the R help mailing list archive at Nabble.com.

I know this is a very elementary question... I could not find a solution looking at old posts. I am unable to access a variable outside the scope of a for loop, even when the variable was defined before the loop: haar <- function() { a = c(1.4560773, 2.3752412, 0.9798882, 3.0909252, 2.3986487, 1.8581543) for (i in c(1:100)) { m = matrix(rnorm(36)+1i*rnorm(36),6) qrm = qr(m) Q = qr.Q(qrm)

I am trying to reproduce the output of a time series example in Koop's book "Analysis of Financial Data". Koop does the example in Excel and I used the ts function followed by the lm function. I am unable to get the exact coefficients that Koop gives - my coefficients are slightly different. After loading the data file and attaching the frame, my code reads: > y = ts(m.cap) >

Hello, I believe the aov() function in R uses a "Type-I sum-of-squares" by default as against "Type-III". This is relevant for me because I am trying to understand ANOVA in R using my knowledge of ANOVA in SPSS. I can only reproduce the results of an ANOVA done using R through SPSS if I specify that SPSS uses a Type-I sum-of-squares. (And yes, I know that when the sample

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

Hello, I think I am beginning to understand what is involved in the so-called "Type-I, II, ..." ANOVAS (thanks to all the replies I got for yesterday's post). I have a question that will help me (and others?) understand it better (or remove a misunderstanding): I know that ANOVA is really a special case of regression where the predictor variable is categorical. I know that there

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

Dear All: I have a clinical study where I would like to compare the demographic information for 2 samples in a study. The demographics include both categorical and continuous variables. I would like to be able to say whether the demographics are significantly different or not. The majority of papers that I have read use multiple techniques to achieve this (e.g., t-test for the continuous

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 Sir I am Amit Nirmalkar, M. Sc. Statistics. I generally use SPSS package for analysis. I wanted to run Conditional Logistic Regression in SPSS but this technique is not available. So I thought of R s/w. I am totally blank about R. Can you please send me few of R. Also how to run Conditional Logistic Regression in R. Thanks -- Amit Nirmalkar [[alternative HTML version deleted]]

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]]