search for: spreadlevelplot

Dear All, I want a transformation which will make the spread of the response at all combinations of 2 factors the same. See for example : boxplot(breaks ~ tension * wool, warpbreaks) The closest I can do is : spreadLevelPlot(breaks ~tension , warpbreaks) spreadLevelPlot(breaks ~ wool , warpbreaks) I want to do : spreadLevelPlot(breaks ~tension * wool, warpbreaks) But I get : > spreadLevelPlot(breaks ~tension * wool , warpbreaks) Error in spreadLevelPlot.formula(breaks ~ tension * wool, warpbreaks) : right-hand...

Dear Ashim, Try spreadLevelPlot(breaks ~ interaction(tension, wool), data=warpbreaks) . I hope this helps, John ----------------------------- John Fox, Professor Emeritus McMaster University Hamilton, Ontario, Canada Web: socialsciences.mcmaster.ca/jfox/ > -----Original Message----- > From: R-help [mailto:r-help-bounc...

Dear All, we need to do : library(car) for the spreadLevelPlot function I forgot to say that. Apologies, Ashim On Sun, Jan 7, 2018 at 10:37 AM, Ashim Kapoor <ashimkapoor at gmail.com> wrote: > Dear All, > > I want a transformation which will make the spread of the response at all > combinations > of 2 factors the same. > > See...

...plot(breaks ~ tension) c. boxplot(breaks ~ interaction(wool,tension)) d. boxplot(breaks ~ wool @ each level of tension) e. boxplot(breaks ~ tension @ each level of wool) Now should we not be making a-e normal and homoscedastic? Should we not make a giant collection of boxplots from a-e and use the SpreadLevelPlot on this entire collection? A second query : (d) and (e) are the distribution of the simple effects of factor wool and tension @ each level of the other. Is that correct? Are (a) and (b) the distribution of the main effect of wool and tension? Please confirm. Best Regards, Ashim On Sun, Jan 7,...

...boxplot(breaks ~ interaction(wool,tension)) >d. boxplot(breaks ~ wool @ each level of tension) >e. boxplot(breaks ~ tension @ each level of wool) > > >Now should we not be making a-e normal and homoscedastic? Should we not >make a giant collection of boxplots from a-e and use the SpreadLevelPlot >on this entire collection? > > >A second query : (d) and (e) are the distribution of the simple effects >of factor wool and tension @ each level of the other. Is that correct? >Are (a) and (b) the distribution of the main effect of wool and tension? >Please confirm. > >...

To detect heteroscedasticity for a multiple linear OLS regression (no time dependencies): What if the residuals vs. fitted values plot shows well behaved residuals (cloud) - but the some of the x versus residuals plots are a megaphone? Also, it seems that textbooks and internet tutorials in R do not agree what is the best plot for detecting heteroscedasticity. What do you use? I found so