[R] Using summaryBy with weighted data

David Freedman dxf1 at cdc.gov
Mon Jan 17 14:51:02 CET 2011


You might use the plyr package to get group-wise weighted means

library(plyr)
ddply(mydata,~group,summarise, b=mean(weights),
c=weighted.mean(response,weights))

hth
david freedman

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