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help for ^kapgof^
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Usage
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^kapgof^ varlist, [level(real 0.05) kappa_options]
Description
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^kapgof^ computes confidence intervals for the kappa statistic
for two indepedent raters and a binary outcome. These confidence
intervals for kappa have desirable small-sample properties. It
also computes confidence intervals for agreement.
This confidence interval is not conditional on kappa being zero
or a pre-specified non-null kappa, as some other procedures are.
It calls @kap@ and returns the same values as this. Although
values for the standard error and z-score are returned, they
are not printed. Presumably, they wouldn't be as useful as
confidence intervals.
Examples
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.^kapgof^ astma1 astma2
computes the kappa statistic and confidence intervals
Remarks
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Bloch & Kraemer (1989) suggest an arcsine transformation. Donner
& Eliasziw (1992) compare this with the goodness-of fit approach
and find that the GOF approach gives coverage levels that are
closer to nominal, even in small samples down to as little
as n=25. I am not aware of any implementations of this arcsine
transformation in any widely available computer program.
The confidence interval given in Fleiss (1981) p.221 is for
a pre-specified non-null kappa.
The confidence intervals for agreement are computed, but
not printed at present. Use ^return list^ to see the
results. They are simply a binomial confidence interval
for the number of agreeing cells as a binomial trial out
of the total number of tries, e.g. (a+b) out of N trials.
References
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Donner, Eliasziw "A goodness-of-fit approach to inference
procedures for the kappa statistic: confidence interval
construction, significance-testing and sample size estimation",
Statistics in Medicine (Stat Med), 1992: vol 11, pp. 1511-1519
Fleiss "The measurement of interrater agreement" in Fleiss:
"Statistical methods for rates and proportions" (Wiley & Sons,
New York) 1981; 212-235.
Bloch, Kraemer, "2x2 kappa coefficients: measures of
agreement or association" Biometrics 1989; 45: 269-287
Author
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Jan Brogger, jan.brogger@@med.uib.no