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

[Chad Danyluck]

I have a data set that includes the identity of a number of Video Coders
who scored participants' behaviors in a video. Every participant was scored
once, but some participants were randomly assigned to have their data
scored twice so I could calculate inter-rater reliabilities. I have
completed the reliability analyses and want to use the average score for
participants who had their behavior coded twice. I'd like to create a 'for
loop' or function that allows me to calculate these column means
iteratively because the number of observations is quite large (*N* =
168). Given the organization of the data, with some participants on
multiple rows, I am not sure how to proceed.

The original data looks something like this:

                        Participant ID Video Coder Score
Observation A                  1            Donald       4
Observation B                  1              Tracy       5
Observation C                  2            Donald       6
Observation D                  3                Sam       2
Observation E                  3              Tracy       3
Observation F                  4            Donald       2
Observation G                  4              Tracy       1
Observation H                  5               Sam       8

When the data processing is completed, I would like the new data set to
look like this:

Participant ID   Score
                 1          4.5
                 2            6
                 3          2.5
                 4          1.5
                 5            8

Any tips or suggestions would be appreciated.

Kind regards,

Chad
-- 
Chad M. Danyluck, MA
PhD Candidate, Psychology
University of Toronto



“There is nothing either good or bad but thinking makes it so.” - William
Shakespeare

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