Re: [R] random uniform sample of points on an ellipsoid (e.g. WG

2007-03-02 Thread R Heberto Ghezzo, Dr
OK, I stand corrected, my previous post generated a point on an ellipsoid as a proyection of an uniform random point in a sphere. now, to generate a random point in a sphere I generate an uniform on one axis and an uniform angle in the second, since the sphere has the property that the

Re: [R] random uniform sample of points on an ellipsoid (e.g. WG

2007-03-01 Thread R Heberto Ghezzo, Dr
Hello, I do not know if I am completely out of it but . . . if x,y,z is a point in a sphere and [u,v,w]'A[u,v,w] = 1 is the equation of an ellipsoid and A = T'T (cholesky) then T.[x,y,z] should be a point in the ellipsoid ? isn't it? Heberto Ghezzo McGill University Montreal Canada

[R] lmer formula

2006-12-18 Thread R Heberto Ghezzo, Dr
Hello, I have some problems trying to write up the formula for lmer. I have 43 subjects ( random factor) which were seen twice ( Visit : repeated measure - fixed). on each visit the patient performed a graded effort exercise ( effort : repeated measures, ordered, fixed 4 levels). So Subject is

[R] Compiling a package

2006-09-01 Thread R Heberto Ghezzo, Dr
Hello, I am in Win-XP R:2.3.0 latest rtools and Perl - of today I got Rcmdr.HH source code and tried to compile it myself copy all directory to R/R-2.3.0/src/library/Rcmdr.HH from R/R-2.3.0/src/library I typed: ..\..\bin\R CMD build --force --binary --auto-zip Rcmdr.HH * checking for file

Re: [R] Correlation adjusted Bonferroni? (was: Multiple tests on repeated measurements)

2006-08-02 Thread R Heberto Ghezzo, Dr
HI, just my 2 cents. Bonferroni et al, assume independent tests, thus p ~ p*k with k the number of tests, in repeated measures, each measure is correlated with the previous, so k is not 2 but 2-q. I do not know q but it should be a function of the correlation between measures, ie the Sigma in