[R] ANOVA of a sort

Claus O'Rourke claus.orourke at gmail.com
Thu Jun 10 01:17:13 CEST 2010

Dear R Help,

I have a general question - I know this is the R list, but I hope
someone can help me out a little as I've always found the help here to
be absolutely fantastic.

I have run a psychological study where participants are given multiple
stimuli and their responses to those stimuli are measured on the same
numerical scale, i.e., the data is something like

Participant Stimulus Measurement
  p1                 s`1            5
  p1                 s`2            6.1
  p1                 s`3            7
  p2                 s`1            4.8
  p2                 s`2            6
  p2                 s`3            6.5
  p3                 s`1            4
  p3                 s`2            7
  p3                 s`3            6

I would like to be able to measure the between participant variability
for my data - i.e., determine whether measurements are relatively
homogeneous across participants and whether there are very strange
outliers (i.e., participants who maybe gave random or purposefully
incorrect answers).

Can anyone point me towards the correct type of tests for quantifying
this?  I have read that a repeated measure ANOVA might be a starting

Many many thanks for any help you can give me!


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