Is there a shortcut way to add a calculated variable to a data frame? For example, I have a data frame with variables first.conv, first.sub, and first.agg. Each cell is -1, 0, or 1. I'd like to generate variables: rwa.sum : sum(first.agg,first.sub,first.conv) rwa.psum : total number (0-3) of vars == 1 rwa.asum : total number (0-3) of vars == -1 rwa.val : sum(abs(first.agg,first.sub,first.conv)) The only way I can think of to do this is to create a separate data.frame to hold the calculated values, then use cbind() to paste the two together. Am I missing an easier option? Thanks. ---------------------------------------------------------------------- Andrew J Perrin - http://www.unc.edu/~aperrin Assistant Professor of Sociology, U of North Carolina, Chapel Hill clists at perrin.socsci.unc.edu * andrew_perrin (at) unc.edu