Performing stats on group of observations
"... trying to figure it out" ?? Not sure what that means.Have you read "An Introduction to R."? If not, do so now. In any case, ?ave is made for what you want, I think (simpler than ?by). As in (if df is your data frame): ave(df$NoFlights,df$Week, FUN= mean) Or, better yet, using ?with and noting that mean is the default for FUN with(df,ave(NoFlights,Week)) Cheers, Bert
On Mon, Jun 24, 2013 at 4:53 PM, Ion Mateescu <ion.matees at gmail.com> wrote:
This may be a simple problem but I spent most of my day today trying to
figure it out, as I am not a programmer. I have a dataframe with
observations from different weeks of the year, numbered. My variable
"week" has values week1, week4, week9, etc. Not all weeks are represented.
I need to calculate statistics and compare means for a measured variable
(no_of_flights) :
Week NoFlights
week1 31.00
week1 31.00
week1 36.00
week1 32.00
week1 30.00
week1 30.00
week1 30.00
week2 31.00
week2 32.00
week1 30.00
week1 31.00
week1 32.00
week23 30.00
week23 35.00
week57 30.00
week1 32.00
week1 33.00
week1 33.00
week2 30.00
week2 33.00
week1 32.00
week1 32.00
week1 33.00
week23 28.00
Any help is appreciated.
River
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Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm