{"id":129,"date":"2009-02-05T21:58:42","date_gmt":"2009-02-06T02:58:42","guid":{"rendered":"http:\/\/www.thejuliagroup.com\/blog\/?p=129"},"modified":"2009-02-05T21:58:51","modified_gmt":"2009-02-06T02:58:51","slug":"baby-steps-to-logistic-regression","status":"publish","type":"post","link":"https:\/\/www.thejuliagroup.com\/blog\/baby-steps-to-logistic-regression\/","title":{"rendered":"Baby Steps to Logistic regression"},"content":{"rendered":"<p><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-full wp-image-130\" title=\"babyeva2\" src=\"http:\/\/www.thejuliagroup.com\/blog\/wp-content\/uploads\/2009\/02\/babyeva2.jpg\" alt=\"babyeva2\" width=\"170\" height=\"226\" \/><\/p>\n<p>Going from the phi coefficient to odds-ratios. Remember the numerator for the phi coefficient was<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-131 alignleft\" title=\"phinum\" src=\"http:\/\/www.thejuliagroup.com\/blog\/wp-content\/uploads\/2009\/02\/phinum.jpg\" alt=\"phinum\" width=\"129\" height=\"35\" \/> well, the odds ratio is the same two numbers DIVIDED rather than subtracted. You might think it is four numbers, but really it is not. The first number is the product of the diagonal cells (see below). The second number is the product of the off-diagonal cells. Let&#8217;s take a look at our data again, first in symbolic form and then the actual numbers.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-medium wp-image-133\" title=\"tablesodds1\" src=\"http:\/\/www.thejuliagroup.com\/blog\/wp-content\/uploads\/2009\/02\/tablesodds1-300x140.jpg\" alt=\"tablesodds1\" width=\"300\" height=\"140\" srcset=\"https:\/\/www.thejuliagroup.com\/blog\/wp-content\/uploads\/2009\/02\/tablesodds1-300x140.jpg 300w, https:\/\/www.thejuliagroup.com\/blog\/wp-content\/uploads\/2009\/02\/tablesodds1.jpg 317w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/p>\n<p>So the odds of a woman doing the dishes are 9:1 , that is for every one woman who doesn&#8217;t do the dishes, there are nine who do. The odds of a man doing the dishes are 1:3, that is, for every three men who don&#8217;t do the dishes, there is one who does.<\/p>\n<p>Here is our formula for the odds ratio:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-134 alignleft\" title=\"oddsratio\" src=\"http:\/\/www.thejuliagroup.com\/blog\/wp-content\/uploads\/2009\/02\/oddsratio.jpg\" alt=\"oddsratio\" width=\"90\" height=\"69\" \/><\/p>\n<p>=\u00a0\u00a0 (10*25)\u00a0 \/(75*90)\u00a0 =\u00a0\u00a0 1\/27<\/p>\n<p>The odds of a man doing the dishes (1\/3) are one-twenty-seventh the odds of a woman doing them (9\/1).<\/p>\n<p>Tomorrow, I will try to find the time\u00a0 to explain how this is intimately related to logistic regression.<\/p>\n<p>But for now, I am going to go home, and, no doubt, eventually do the dishes.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Going from the phi coefficient to odds-ratios. Remember the numerator for the phi coefficient was well, the odds ratio is the same two numbers DIVIDED rather than subtracted. You might think it is four numbers, but really it is not. The first number is the product of the diagonal cells (see below). The second number&#8230;<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_kad_post_classname":"","_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[1,11],"tags":[],"class_list":["post-129","post","type-post","status-publish","format-standard","hentry","category-dr-de-mars-general-life-ramblings","category-statistics"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.thejuliagroup.com\/blog\/wp-json\/wp\/v2\/posts\/129","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.thejuliagroup.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.thejuliagroup.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.thejuliagroup.com\/blog\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/www.thejuliagroup.com\/blog\/wp-json\/wp\/v2\/comments?post=129"}],"version-history":[{"count":2,"href":"https:\/\/www.thejuliagroup.com\/blog\/wp-json\/wp\/v2\/posts\/129\/revisions"}],"predecessor-version":[{"id":136,"href":"https:\/\/www.thejuliagroup.com\/blog\/wp-json\/wp\/v2\/posts\/129\/revisions\/136"}],"wp:attachment":[{"href":"https:\/\/www.thejuliagroup.com\/blog\/wp-json\/wp\/v2\/media?parent=129"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.thejuliagroup.com\/blog\/wp-json\/wp\/v2\/categories?post=129"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.thejuliagroup.com\/blog\/wp-json\/wp\/v2\/tags?post=129"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}