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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

...eal 04/01/1991 5 .... How to select the earliest (or latest) test result from all subjects? Thank you. Regards, CH -- "The scientists of today think deeply instead of clearly. One must be sane to think clearly, but one can think deeply and be quite insane." Nikola Tesla http://www.macgrass.com

...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 type of graph. Regards, H -- CH Chan Research Assistant - KWH http://www.macgrass.com

...se this function, it can do the lillie's test but failed to do the glm. What's wrong with my code? Regards, CH -- "The scientists of today think deeply instead of clearly. One must be sane to think clearly, but one can think deeply and be quite insane." Nikola Tesla http://www.macgrass.com

...g "<-" into "< -" and I have to use "=" instead. (I think "=" is confusing.) And I think it is not related to the theme as well. Is there any clue to solve this? I am using Wordpress 2.9.2. Regards, CH -- CH Chan Research Assistant - KWH http://www.macgrass.com

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

...this in R for Mac OS X Aqua GUI. I checked the relevant document but no specific steps for Mac OS X. Regards, Ch Chan -- "The scientists of today think deeply instead of clearly. One must be sane to think clearly, but one can think deeply and be quite insane." Nikola Tesla http://www.macgrass.com

Hello, is there an up-to-date reference for how many people use R? I'm giving an R demo and want to cite wonderful R usage stats. How many people use it (or download it)? How often is R used in peer-reviewed pubs, etc. Is there any whiz-bang citation that says something like "R is great and developed by the best minds in statistical computing." Any thoughts? -Andy

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

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 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

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]]

...e proportional assumption) in R. Using the AML example. fit <- survfit(Surv(time, status) ~ x, data=aml) length(fit$surv) #20 as the length of fit$surv is shorter than aml$x and aml$time. I don't know how to plot. Thank you. Regards, CH -- CH Chan Research Assistant - KWH http://www.macgrass.com

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]]

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