[R] Help - linear regression
Hi, I am trying a linear regression model where the dependent variable is the size of the heart corrected for the patient's height and weight. This is labelled as LAVI. The independent variables are race (european or non-eurpoean), age, sex (male or female) of the patient and whether they have diabetes and high blood pressure. sample size 2000 patients selected from a community. when I model model1<-lm(lavi~age+sex+race+diabetes+hypertension, data=tb1) and model2<-lm(lavi~age+sex+age*race+diabetes+hypertension, data=tb1) in the first model race comes out as a significant predictor (p<0.005) where as in the second model race is not a significant predictor of lavi (p=.076) in my dataset mean age is 55.2 years in the non-europeans and 56.7 years in the europeans (p <0.0001 by t.test). should I or should I not include the interaction (age*race) in the model. Is it an acceptable rule to put in interactions if there is a significant relation between the indepenedent variables in univariate analyses. Many thanks bragadeesh _ Helping your favorite cause is as easy as instant messaging. You IM, we give. [[alternative HTML version deleted]] __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
[R] help_R2.5 updating
Hi, I run windows vista ultimate in my laptop and run R 2.5 I am trying to update the packages but it comes up with an error message ""Warning in install.packages(update[instlib == l, "Package"], l, contriburl = contriburl, : 'lib' is not writable Error in install.packages(update[instlib == l, "Package"], l, contriburl = contriburl, : unable to install packages" I am the adminsitrator on this computer and logged in as administrator. can anyone advise. I treid to switch off most security - windows firewall is off and so is macfee. many thanks for your advise bragadeesh _ Climb to the top of the charts! Play Star Shuffle: the word scramble challenge with star power. [[alternative HTML version deleted]] __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
