search for: coghlan

...ficantly less than 1. How can I do this in R? I'm also interested in comparing the slopes of two regressions: fm1 <- lm (x ~ y) fm2 <- lm (a ~ b) and asking if the slope of fm1 is less than the slope of fm2. Is this easy to do in R? I will be very grateful for any help. regards, Avril Coghlan (University College Dublin, Ireland)

...s of the principal components (as stored in 'scores'), and why is the total variance calculated by summing the squared 'sdev' values not equal to 4? Sorry if I have misunderstood something obvious. I would be grateful for help as I'm a bit confused.. Kind regards, Avril Avril Coghlan Cork, Ireland [[alternative HTML version deleted]]

...alue distribution to the Y data. However, I'm not sure how to do this. I am wondering is there a way to use the extreme value distribution functions in R to test the hypothesis that the maximum of Y (for a particular X) is correlated with X? I would appreciate advice very much. regards Avril Coghlan -- The Wellcome Trust Sanger Institute is operated by Genome Research Limited, a charity registered in England with number 1021457 and a company registered in England with number 2742969, whose registered office is 215 Euston Road, London, NW1 2BE.

...dering can I combine X1 and X2 in a logistic regression to predict Y, using all the data for X1, even though there are NAs in the X2 data? Or do I have to take only the cases for which there is data for both X1 and X2? (marked with *s above) I will be very grateful for any help, sincerely, Avril Coghlan University College Dublin, Ireland

Hello, I have been looking for functions for calculating the within-groups variance and between-groups variance, for the case where you have several numerical variables describing samples from a number of groups. I didn't find such functions in R, so wrote my own versions myself (see below). I can calculate the within- and between-groups variance for the Sepal.length variable (iris[1]) in

...iams (1959) and Steiger. There is also a test called Hotelling's t test. I'm wondering does anyone know whether I can somehow carry out any of these using an R package, or compare non-independent correlations using R by some other method? I will greatly appreciate any help, thankyou, Avril Coghlan (University College Dublin, Ireland)

...let for beginners like myself (I am studying Stats, and mostly wrote it to help myself study and understand this material), but thought it could possibly be useful to some other Stats/R beginners.. I would be grateful for any suggestions for improvements. Kind Regards, Avril Avril Coghlan Cork, Ireland [[alternative HTML version deleted]]

Hello, I have a small statistics question, and as I'm quite new to statistics and R, I'm not sure if I'm doing things correctly. I am looking at two quantitative variables (x,y) that are correlated. When I divide the data set according to a categorical variable z, then x and y are more poorly correlated when z = A than when z = B (see attached figure). In fact x and y are two