[redirected from R-devel: this really belongs on R-help] I have two sets of time-series that I imported from Excel using RODBC and placed in "securities" and "factors". What I need to do is generate t-scores for each security-factor pair. I tried the following: t1 <- t.test(securities[,3:42], factors[,2:41], var.equal=TRUE) ANSWER: If securities and factors are both data frames then something like m1 <- mapply(t.test,securities[3:42],factors[2:41],SIMPLIFY=FALSE, MoreArgs=list(var.equal=TRUE)) (note the lack of commas in the square brackets -- this extracts the columns you want as sublists, although it might work with commas as well, haven't tried it) will give you a list of t-test results. If all you want is the t-statistic, something like sapply(m1,"[[","statistic") should do it. Poke around in the documentation (?mapply, ?sapply, etc.) to see why this all works. -- 620B Bartram Hall bolker at zoo.ufl.edu Zoology Department, University of Florida http://www.zoo.ufl.edu/bolker Box 118525 (ph) 352-392-5697 Gainesville, FL 32611-8525 (fax) 352-392-3704