Greg, Dennis - thanks for your input, I really appreciate the feedback, as it is not easy to source.
In terms of the data; I've described it as 20 columns, which is the smallest dataset, but this can run to 320 columns, so in some cases there is likely to be enough power to detect non-normality. That said, a better solution would be useful. As a first approximation, I looked at the mean/median ratio to indicate simple skew in the data - which suggested that most of the data was normally distributed. I took the 'nuggets' to be those with a mean/median ratio in the top or bottom 1% of the data. This was a small group - overall the data appears relatively normally distributed within rows. The aim is really to find those nuggets with significantly non-normal distributions. My hope was to be able to take the tails of the p-values for Shapiro-Wilk, or some similar test, and find these enriched with nuggets. This may not be an appropriately robust approach - but is there a better option? One idea was to sort the data in each row, and perform a linear regression. For normal distributions I am expecting the intercept to be close to the mean. Using the (intercept-mean) and p-values for the fit of the regression was again another way to filter out the nuggets in the dataset. If it helps, the nuggets I am expecting are either grouped 80% grouped around the mean with 20% forming a uni-directional tail, or an approximate bimodal distribution. As I'd imagine is obvious - I don't have an ideal solution to finding these nuggets, and so coming up with the R code to do so is harder still. If anybody has insight into this sort of problem, and can point me in the direction of further reading, that would be helpful. If there is a ready-made solution, even better! As I said, thanks for your time with this... -- View this message in context: http://r.789695.n4.nabble.com/Finding-non-normal-distributions-per-row-of-data-frame-tp3259439p3261203.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.
