search for: homocedasticity

Dear All My data consists in 96 groups, each one with 10 observations. Levene's test suggests that the variances are not equal, and therefore I have tried to apply the classical transformations to have homocedasticity in order to be able to use ANOVA. Unfortunately, no transformation that I have used transforms my data into data with homocedasticity. The histogram of variances is at http://phhs80.googlepages.com/hist1.png Is someone able to suggest to me a transformation to overcome the problem of heterocedast...

An embedded and charset-unspecified text was scrubbed... Name: not available URL: <https://stat.ethz.ch/pipermail/r-help/attachments/20091125/3f0e364b/attachment-0001.pl>

...credit. 2) What do the experts think of the green trend lines? Are they effective for spotting residuals/predictor variables relationships or are they misleading? 3) In the future, I would like to plot a grey shaded region approximately corresponding to the dispersion cloud, in order to appreciate homocedasticity or the lack thereof.  Perhaps this could be done by calculating "upper and lower limit trend lines"? Any ideas on how to do this? Thanks in advance, José Loreto Romero Palma [[alternative HTML version deleted]]

Hi everyone, I?m a student and relatively new to R so apologies in advance if this question seems stupid or obvious to you. I have collected a dataset with about 60 species of diatoms (count data from 19 different sample sites) and environmental variables for each site (salinity, pH, etc.). It?s all in the same dataset but distinct in R through the functions below diat <- diatom [, 1:60]