I wonder if someone could help me with the following, I am looking to
calculate intra rater and inter rater correlations on the following data
set. A continuous variable has been measured by 6 trainees on three
different subjects (the three subjects have differing degrees of disease:
small, moderate and large). All 6 trainees repeated the measurements on
the three subjects on two separate occasions.
I have applied ICC as a measure for the agreement between the 6 raters;
however STATA outputs 0* for the ICC whereas the data appears to show a
reasonable agreement in measures between raters:
rater time1 time2
JT 22.5 22.5
KD 22.5 22.5
WD 22.5 22.5
NC 22 23
RP 22.5 22
ES 21.5 23
. loneway var1 rater
One-way Analysis of Variance for var1: measure2
Number of obs = 12
R-squared = 0.0870
Source SS df MS F Prob > F
-------------------------------------------------------------------------
Between rater .16666667 5 .03333333 0.11 0.9845
Within rater 1.75 6 .29166667
-------------------------------------------------------------------------
Total 1.9166667 11 .17424242
Estimated SD of rater effect .
Estimated SD within rater .5400617
Est. reliability of a rater mean 0.00000*
(evaluated at n=2.00)
(*) Truncated at zero.
Also I wondered what measure I should use to consider the agreement between
the repeat measures (should this be ICC also, and if so how should the data
be set up, apologies to ask a basic question). Finally, is there anyway to
consider the three subjects data together, i.e to combine the info for the
small, moderate and large.
Many thanks for any help you can provide.
Kindest regards
Emma
