{"id":187,"date":"2006-05-01T16:18:09","date_gmt":"2006-05-01T22:18:09","guid":{"rendered":"http:\/\/hunch.net\/?p=187"},"modified":"2006-05-01T16:18:20","modified_gmt":"2006-05-01T22:18:20","slug":"a-conversation-between-theo-and-pat","status":"publish","type":"post","link":"https:\/\/hunch.net\/?p=187","title":{"rendered":"A conversation between Theo and Pat"},"content":{"rendered":"<p><b>Pat (the practitioner)<\/b> I need to do multiclass classification and I only have a decision tree.<\/p>\n<p><b>Theo (the thoeretician)<\/b> Use an <a href=\"http:\/\/www.cs.cmu.edu\/afs\/cs\/project\/jair\/pub\/volume2\/dietterich95a.pdf\">error correcting output code<\/a>.<\/p>\n<p><b>Pat<\/b> Oh, that&#8217;s cool.  But the created binary problems seem unintuitive.  I&#8217;m not sure the decision tree can solve them.<\/p>\n<p><b>Theo<\/b> Oh?  Is your problem a decision list?  <\/p>\n<p><b>Pat<\/b> No, I don&#8217;t think so.<\/p>\n<p><b>Theo<\/b> Hmm.  Are the classes well separated by axis aligned splits?<\/p>\n<p><b>Pat<\/b> Err, maybe.  I&#8217;m not sure.<\/p>\n<p><b>Theo<\/b> Well, if they are, under the IID assumption I can tell you how many samples you need.<\/p>\n<p><b>Pat<\/b> IID?  The data is definitely not IID.<\/p>\n<p><b>Theo<\/b> Oh dear.<\/p>\n<p><b>Pat<\/b> Can we get back to the choice of ECOC?  I suspect we need to build it dynamically in response to which subsets of the labels are empirically separable from each other.<\/p>\n<p><b>Theo<\/b> Ok.  What do you know about your problem?<\/p>\n<p><b>Pat<\/b> Not much.  My friend just gave me the dataset.<\/p>\n<p><b>Theo<\/b> Then, no one can help you.<\/p>\n<p><b>Pat<\/b> (What a fuzzy thinker.  Theo keeps jumping to assumptions that just aren&#8217;t true.)<\/p>\n<p><b>Theo<\/b> (What a fuzzy thinker.  Pat&#8217;s problem is unsolvable without making extra assumptions.)<\/p>\n<p>I&#8217;ve heard variants of this conversation several times.  The fundamental difference in viewpoint is the following: <\/p>\n<ol>\n<li>Theo lives in a world where he chooses the problem to solve based upon learning model (and assumptions) used.  <\/li>\n<li>Pat lives in a world where the problem is imposed on him.<\/li>\n<\/ol>\n<p>I&#8217;d love for these confusions to go away, but there is no magic wand.  The best advice seems to be: listen carefully and avoid assuming to much in what you hear.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Pat (the practitioner) I need to do multiclass classification and I only have a decision tree. Theo (the thoeretician) Use an error correcting output code. Pat Oh, that&#8217;s cool. But the created binary problems seem unintuitive. I&#8217;m not sure the decision tree can solve them. Theo Oh? Is your problem a decision list? Pat No, &hellip; <\/p>\n<p class=\"link-more\"><a href=\"https:\/\/hunch.net\/?p=187\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;A conversation between Theo and Pat&#8221;<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[29],"tags":[],"class_list":["post-187","post","type-post","status-publish","format-standard","hentry","category-machine-learning"],"_links":{"self":[{"href":"https:\/\/hunch.net\/index.php?rest_route=\/wp\/v2\/posts\/187","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hunch.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hunch.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hunch.net\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/hunch.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=187"}],"version-history":[{"count":0,"href":"https:\/\/hunch.net\/index.php?rest_route=\/wp\/v2\/posts\/187\/revisions"}],"wp:attachment":[{"href":"https:\/\/hunch.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=187"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hunch.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=187"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hunch.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=187"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}