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May I ask a clinical question? For a trial, we have a treatment group of small size, say 30 patients. We want to selectmatching control patients from a bigger group (100 patients) in terms of several clinical variables, such as age, tumor stage etc. This practice is to select the closest matching set of control cases. I wonder if R has any routine or package that can help with this problem.

Dear all, I have a problem. I have m variables each of which has n observations. I want to calculate pairwise correlation among the m variables and store the values in a m x m matrix. It is extremely slow to use nested 'for' loops if m and n are large. Is there any efficient alternative to do this? Many thanks for your suggestions!! Bill

Dear all, Does any one know how to remove part of the string? For example, "LTA4H||Leukotriene A4 hydrolase" is a gene name plus gene description. I hope to remove "||Leukotriene A4 hydrolase". What would be the R code to do that using gsub()? Many thanks! Bill

Dear all, Does any one know if any R package or function can do Ordinary Least Products regression? Many thanks! Bill

Hi all, I read in a column which looks like "chr1:000889594-000889638", and need to break them into three columns like "chr1:", "000889594" and "000889638". How shall I do in R. Thanks a lot for your suggestions! Bill

Hi friends, Does anyone know how to make truncated y axis with cut mark (\\) in R plot? Many thanks! Bill

Dear all, Does any one know how to calculate the risk (death rate) at some time point (say 5 yrs) based on Kaplan-Meier curve in coxph model in R? I know how to fit the survival data with coxph. But need to calculate risk at some time point. Many thanks. Bill