Intra-obsever variability

[Fredrick orwa]

Dear colleagues can I still use kap in stata for intra-observer variability? I have two readings by the same reader trying to asses presence of radiologically confirmed pneumonia. With 1 denoting presence of rcp, 0 denoting absence of rcp.Have a look at the data:

input float(reader1_a reader1_b)
1 1
0 0
1 1
1 1
0 1
1 0
1 1
end

can I do something like;
kap reader1_a reader1_b?

[daniel klein]

Cohen's kappa (and other chance-corrected agreement coefficients; for alternative coefficients, see kappaetc from SSC) are one way of looking at the agreement between measures/ratings of the same subject. Whether those different measures represent ratings/scores of different raters/judges/observers or different readings is not relevant to the mathematics. It might be conceptually harder to establish "independence" (however defined) between two readings by the same reader as a plausible Nullhypothesis to test against, though.

[Fredrick orwa]

Thanks Daniel Klein, so this means I can do;
kap reader1_a reader1_b as I asked before to asses intra-observer variability for reader1