[R] Averaging column scores when participants vary in number of observations

[John Kane]

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.huang at protective.com
> Sent: Thu, 19 Feb 2015 17:36:19 -0800 (PST)
> To: r-help at 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:
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> Sent from the R help mailing list archive at Nabble.com.
> 
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