Dear R People: Thanks to Ben Bolker, Brian Ripley, Peter Wolf, Reid Huntsinger, and Greg Warnes for their quick responses. The majority suggested using filter() as found in the ts package. Peter Wolf suggested: diff(cumsum((c(0,y)),lag=12)/12 and Greg suggested his own code, which he kindly included. This was such a big help! Thanks again! Also thanks to anyone that I may have missed! Erin -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._