And just to muddy the waters more here's another way to do it using the handy plyr package where the data.frame is "dat1"
library(plyr) ddply(dat1, .(Participant.ID), summarize, mean = mean(Score)) John Kane Kingston ON Canada > -----Original Message----- > From: js.hu...@protective.com > Sent: Thu, 19 Feb 2015 17:36:19 -0800 (PST) > To: r-help@r-project.org > Subject: Re: [R] Averaging column scores when participants vary in number > of observations > > Hi, > > Another implication: > >> data1 > Observation Participant.ID Video.Coder Score > 1 A 1 Donald 4 > 2 B 1 Tracy 5 > 3 C 2 Donald 6 > 4 D 3 Sam 2 > 5 E 3 Tracy 3 > 6 F 4 Donald 2 > 7 G 4 Tracy 1 > 8 H 5 Sam 8 >> tapply(data1$Score,data1$Participant.ID,mean) > 1 2 3 4 5 > 4.5 6.0 2.5 1.5 8.0 > > > > > -- > View this message in context: > http://r.789695.n4.nabble.com/Re-Averaging-column-scores-when-participants-vary-in-number-of-observations-tp4703549p4703561.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ____________________________________________________________ Can't remember your password? Do you need a strong and secure password? Use Password manager! It stores your passwords & protects your account. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
