kapprevi



Stata help for kapprevi

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help for kapprevi
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Dependence of kappa statistic on true prevalence

kapprevi , r1(#sens #spec) r2(#sens #spec) [ nograph scatter_options ]

Description

kapprevi provides a graphical representation of the kappa statistic as a function of the true prevalence of the characteristic in the population, given specified values of sensitivity and specificity for two raters. It is an immediate command, see help immed. Options

r1(#sens #spec) specifies the sensitivity and specificity of rater 1. These numbers have to range between 0 and 1.

r2(#sens #spec) specifies the sensitivity and specificity of rater 2. These numbers have to range between 0 and 1.

nograph suppresses graphical output.

scatter_options are any of the scatter options.

Examples

. kapprevi, r1(0.90 0.95) r2(0.70 .99) . kapprevi, r1(0.90 0.95) r2(0.90 .95) . kapprevi, r1(0.70 0.90) r2(0.70 .90) ysize(4) xsize(4) . kapprevi, r1(0.70 0.90) r2(0.70 .90) . kapprevi, r1(0.90 0.95) r2(0.70 .99) ysize(4) xsize(4) scheme(vg_blue)

Authors

Nicola Orsini, Division of Nutritional Epidemiology, IMM, Karolinska Institutet, Sweden Debora Rizzuto, Division of Geriatric Epidemiology, Department of Neurotec, Karolinska Institutet, Sweden

Reference

Thompson W.D and Walter S.D. A reappraisal of the kappa coefficient, J Clin Epidemiol, 1988, Vol.41, n.10, pp.949-959 Support

http://nicolaorsini.altervista.org nicola.orsini@ki.se

Also see

On-line: help for kappa

Worked examples for kapprevi

Click here to run or save the do-file

. capture net install http://nicolaorsini.altervista.org/stata/kapprevi

. . which kapprevi c:\ado\stbplus\k\kapprevi.ado *! v 1.0.0 N.Orsini & D.Rizzuto 19Oct2005

. . kapprevi, r1(0.90 0.95) r2(0.70 .99)

Maximum value (kappa, prevalence) = (0.632, 0.294)

. kapprevi, r1(0.90 0.95) r2(0.90 .95)

Maximum value (kappa, prevalence) = (0.729, 0.421)

. kapprevi, r1(0.70 0.90) r2(0.70 .90) ysize(4) xsize(4)

Maximum value (kappa, prevalence) = (0.385, 0.398)

. kapprevi, r1(0.70 0.90) r2(0.70 .90) title(Dependence of kappa on prevalence)

Maximum value (kappa, prevalence) = (0.385, 0.398)

. kapprevi, r1(0.90 0.95) r2(0.70 .99) ysize(4) xsize(4) scheme(vg_blue)

Maximum value (kappa, prevalence) = (0.632, 0.294)


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