{"id":1019,"date":"2015-06-05T20:55:24","date_gmt":"2015-06-05T19:55:24","guid":{"rendered":"https:\/\/blogs.bmj.com\/adc\/?p=1019"},"modified":"2015-06-03T15:52:21","modified_gmt":"2015-06-03T14:52:21","slug":"statsminiblog-cluster-analysis","status":"publish","type":"post","link":"https:\/\/blogs.bmj.com\/adc\/2015\/06\/05\/statsminiblog-cluster-analysis\/","title":{"rendered":"StatsMiniBlog: Cluster analysis"},"content":{"rendered":"<p><a href=\"https:\/\/blogs.bmj.com\/adc\/files\/2014\/02\/20140204-233354.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"alignleft size-full wp-image-855\" src=\"https:\/\/blogs.bmj.com\/adc\/files\/2014\/02\/20140204-233354.jpg\" alt=\"20140204-233354.jpg\" width=\"180\" height=\"76\" \/><\/a>Lumps and groups and clumps and factors &#8230; all sorts of ways of describing how Things Can Be Similar.<\/p>\n<p>Cluster analysis is a statistical term that refers to an approach &#8211; not a particular method &#8211; that seeks to work out how to group items together so those in the same group are maximally similar to each other, and maximally different to things in other groups. Like cats and dogs.\u00a0<!--more--><\/p>\n<p>This might look at minimising the distance on two axes, like this pretty picture:<img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"http:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/b\/b7\/SLINK-Gaussian-data.svg\/186px-SLINK-Gaussian-data.svg.png\" alt=\"\" width=\"186\" height=\"200\" \/><\/p>\n<p>Or it might try and see how things group, and then sub-group, and then sub-sub-group, like this\u00a0dendrogram:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"http:\/\/dali.feld.cvut.cz\/ucebna\/matlab\/toolbox\/stats\/refea143.gif\" alt=\"\" width=\"194\" height=\"174\" \/><\/p>\n<p>(which might remind you of our <a href=\"https:\/\/blogs.bmj.com\/adc\/2015\/03\/31\/statsminiblog-recursive-partitioning\/\">recursive partitioning <\/a>post)<\/p>\n<p>The exact techniques are\u00a0chosen with some common sense (what&#8217;s the grouping you think will be there), some computing power issues, and some fiddling (like most stats), and like most stats, if you pick a daft model you&#8217;ll get a daft answer. But the basic idea is simple: does this look more like Cluster 1 (dogs) or Cluster 2 (rabbits)<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"http:\/\/heartymagazine.com\/wp-content\/uploads\/2011\/02\/fred-conrad-dog-photos-nytimes-1.png\" alt=\"\" width=\"290\" height=\"207\" \/><\/p>\n<p>&#8211; Archi<!--TrendMD v2.4.8--><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Lumps and groups and clumps and factors &#8230; all sorts of ways of describing how Things Can Be Similar. Cluster analysis is a statistical term that refers to an approach &#8211; not a particular method &#8211; that seeks to work out how to group items together so those in the same group are maximally similar [&#8230;]<\/p>\n<p><a class=\"btn btn-secondary understrap-read-more-link\" href=\"https:\/\/blogs.bmj.com\/adc\/2015\/06\/05\/statsminiblog-cluster-analysis\/\">Read More&#8230;<\/a><\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2676],"tags":[],"class_list":["post-1019","post","type-post","status-publish","format-standard","hentry","category-stats"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.3 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>StatsMiniBlog: Cluster analysis - ADC Online Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/blogs.bmj.com\/adc\/2015\/06\/05\/statsminiblog-cluster-analysis\/\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"StatsMiniBlog: Cluster analysis - ADC Online Blog\" \/>\n<meta property=\"og:description\" content=\"Lumps and groups and clumps and factors &#8230; all sorts of ways of describing how Things Can Be Similar. 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