{"id":957,"date":"2014-07-16T21:40:39","date_gmt":"2014-07-16T20:40:39","guid":{"rendered":"http:\/\/stg-blogs.bmj.com\/adc\/?p=957"},"modified":"2014-09-12T15:34:57","modified_gmt":"2014-09-12T14:34:57","slug":"statsminiblog-kappa","status":"publish","type":"post","link":"https:\/\/stg-blogs.bmj.com\/adc\/2014\/07\/16\/statsminiblog-kappa\/","title":{"rendered":"StatsMiniBlog: Kappa"},"content":{"rendered":"

\"20140205-091454.jpg\"<\/a>
\nAfter a short pause while brain cells were diverted elsewhere<\/a>, we’re returning with the critically acclaimed (well, slightly positively tweeted) StatsMiniBlog series.<\/p>\n

(As an aside – do let me know via comments, Facebook or Twitter if there’s an issue you’d like to see covered)<\/p>\n

Kappa (\u03ba) is a measure of agreement, usually between two observers of a dichotomous outcome although there are variants for multiple observers. \u00a0It gives you a measure of what agreement you see that is ‘beyond chance’<\/p>\n

<\/p>\n

The idea is that if you got two observers\u00a0to report on the colour of\u00a0balls emerging from a bag, and in reality there were 5 blue and 5 yellow,\u00a0if the\u00a0observers didn’t look at them and just guessed you would expect them both to be right 0.5 * 0.5 = 0.25 (25%) of the time.<\/p>\n

Anything over this is “agreement beyond chance”.<\/p>\n

The value given to Kappa reflects the degree of agreement, 0 is perfect disagreement, 1, perfect agreement, in between is usually interpreted<\/p>\n\n\n\n\n\n\n\n\n
Kappa
\n(\u03ba)<\/th>\n		Strength of Agreement<\/th>\n<\/tr>\n
<0.20<\/td>\nPoor<\/td>\n<\/tr>\n
0.21-0.4<\/td>\nFair<\/td>\n<\/tr>\n
0.41-0.6<\/td>\nModerate<\/td>\n<\/tr>\n
0.61-0.8<\/td>\nGood<\/td>\n<\/tr>\n
0.81-1.0<\/td>\nExcellent<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

 <\/p>\n

How good you ‘need’ this to be depends upon what you’re using it for. In the same way there is no “right” wine to go with a meal, there is no “correct” kappa value.<\/p>\n

– Archi<\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

After a short pause while brain cells were diverted elsewhere, we’re returning with the critically acclaimed (well, slightly positively tweeted) StatsMiniBlog series. (As an aside – do let me know via comments, Facebook or Twitter if there’s an issue you’d like to see covered) Kappa (\u03ba) is a measure of agreement, usually between two observers […]<\/p>\n

Read More…<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[79],"tags":[],"class_list":["post-957","post","type-post","status-publish","format-standard","hentry","category-archimedes"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/posts\/957","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/comments?post=957"}],"version-history":[{"count":0,"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/posts\/957\/revisions"}],"wp:attachment":[{"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/media?parent=957"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/categories?post=957"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/tags?post=957"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}