{"id":1259,"date":"2016-03-09T20:48:33","date_gmt":"2016-03-09T19:48:33","guid":{"rendered":"http:\/\/stg-blogs.bmj.com\/adc\/?p=1259"},"modified":"2016-02-24T16:58:39","modified_gmt":"2016-02-24T15:58:39","slug":"statsminiblog-middling-differences","status":"publish","type":"post","link":"https:\/\/stg-blogs.bmj.com\/adc\/2016\/03\/09\/statsminiblog-middling-differences\/","title":{"rendered":"StatsMiniBlog: Middling differences"},"content":{"rendered":"<p><img loading=\"lazy\" decoding=\"async\" class=\"alignleft wp-image-1164\" src=\"https:\/\/stg-blogs.bmj.com\/adc\/files\/2015\/09\/calculator-97842_640-282x300.png\" alt=\"calculator-97842_640\" width=\"155\" height=\"165\" srcset=\"https:\/\/stg-blogs.bmj.com\/adc\/files\/2015\/09\/calculator-97842_640-282x300.png 282w, https:\/\/stg-blogs.bmj.com\/adc\/files\/2015\/09\/calculator-97842_640.png 602w\" sizes=\"auto, (max-width: 155px) 100vw, 155px\" \/>Is there a difference between these two <a href=\"https:\/\/stg-blogs.bmj.com\/adc\/2013\/06\/12\/statsminiblog-parametric-like-paramedic-or-paralegal\/\">non-parametric groups<\/a>? (For example, the duration of cough after bronchiolitis&#8230;)<\/p>\n<p>&nbsp;<\/p>\n<table width=\"780\">\n<tbody>\n<tr>\n<td width=\"195\">&nbsp;<\/p>\n<p>Time to cough resolution (days)<\/p>\n<p>&nbsp;<\/td>\n<td width=\"195\">\u00a0Rx A:\u00a0Median 15 days<\/td>\n<td width=\"195\">\u00a0Rx B: Median 15 days<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>You&#8217;d want to see a <a href=\"https:\/\/stg-blogs.bmj.com\/adc\/2013\/06\/30\/statsminiblog-significance-tests-step-two\/\">stats test though<\/a>, wouldn&#8217;t you. <!--more-->So what if it was ..<\/p>\n<table style=\"height: 125px\" width=\"832\">\n<tbody>\n<tr>\n<td width=\"195\">Time to cough resolution (days)<\/td>\n<td width=\"195\">\u00a0Rx A:<\/p>\n<p>Median 15 days<\/td>\n<td width=\"195\">\u00a0Rx B:<\/p>\n<p>Median 15 days<\/td>\n<td width=\"195\">\u00a0Median Difference<\/p>\n<p>1.0 days (95% CI -1.0 to 2.0)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Hang on! You might say. Those medians are identical &#8211; how can that median difference be 1.0 ?<\/p>\n<p>&nbsp;<\/p>\n<p>Well &#8211; there&#8217;s a difference between a\u00a0Median Difference and a the difference between the group medians. The latter is what it sounds like, and is tested with them <a href=\"https:\/\/stg-blogs.bmj.com\/adc\/2015\/06\/30\/statsminiblog-choosing-a-test\/\">non-parametric testy <\/a>things. The former is trickier &#8230;<\/p>\n<p>Take the durations of cough and put them side by side.<\/p>\n<p>Now take the difference between those pairings you&#8217;ve got.<\/p>\n<p>Now rank the resulting\u00a0&#8220;difference between those pairings&#8221;, and take the 50%ile.<\/p>\n<p>That&#8217;s the median difference (the median of the differences).<\/p>\n<p>Statisticians, huh?<\/p>\n<ul>\n<li>Archi<\/li>\n<\/ul>\n<p><!--TrendMD v2.4.8--><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Is there a difference between these two non-parametric groups? (For example, the duration of cough after bronchiolitis&#8230;) &nbsp; &nbsp; Time to cough resolution (days) &nbsp; \u00a0Rx A:\u00a0Median 15 days \u00a0Rx B: Median 15 days You&#8217;d want to see a stats test though, wouldn&#8217;t you. [&#8230;]<\/p>\n<p><a class=\"btn btn-secondary understrap-read-more-link\" href=\"https:\/\/stg-blogs.bmj.com\/adc\/2016\/03\/09\/statsminiblog-middling-differences\/\">Read More&#8230;<\/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":[2676],"tags":[],"class_list":["post-1259","post","type-post","status-publish","format-standard","hentry","category-stats"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/posts\/1259","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=1259"}],"version-history":[{"count":0,"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/posts\/1259\/revisions"}],"wp:attachment":[{"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/media?parent=1259"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/categories?post=1259"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/tags?post=1259"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}