{"id":377,"date":"2013-03-06T21:08:20","date_gmt":"2013-03-06T20:08:20","guid":{"rendered":"https:\/\/blogs.bmj.com\/adc-archimedes\/?p=377"},"modified":"2013-03-06T21:08:20","modified_gmt":"2013-03-06T20:08:20","slug":"harms-safety-and-certainties","status":"publish","type":"post","link":"https:\/\/blogs.bmj.com\/adc\/2013\/03\/06\/harms-safety-and-certainties\/","title":{"rendered":"Harms, safety and certainties"},"content":{"rendered":"<figure style=\"width: 220px\" class=\"wp-caption alignleft\"><img loading=\"lazy\" decoding=\"async\" alt=\"\" src=\"http:\/\/www.sogmin.org\/images\/child%20scratch.jpg\" width=\"220\" height=\"307\" \/><figcaption class=\"wp-caption-text\">Uncertainties<\/figcaption><\/figure>\n<p>How you know about stuff you don&#8217;t know about is a fascinating philosophical, statistical and downright practical topic.<\/p>\n<p>There&#8217;s the issue of &#8216;unknown unknowns&#8217; &#8211; stuff you didn&#8217;t know you didn&#8217;t know &#8211; that can be frighteningly and sometimes dangerous. (How may of you know that failure to thrive is a common manifestation of a midline low grade brain tumour?). Then there&#8217;s the issue of missing information from trials &#8211; failure to collect it can lead to underpowered estimates and an inability to get to an answer and wasting the effort of all the patients. And there&#8217;s the issue of suppressed, unpublished or fraudulent stuff &#8211; but more of that in a different blog post.<\/p>\n<p>Beyond that is just stuff that hasn&#8217;t happened yet &#8211; for example, if we give 100 children on immunosupressive therapy probiotic yoghurts and see a reduction of diarrhoea, and no cases of infection, are we happy that the yoghurt is giving some tummy loving cuddles and isn&#8217;t dangerous? <!--more-->How many pots of the white stuff do we need to see eaten before we stop worrying about <a href=\"http:\/\/jcm.asm.org\/content\/48\/11\/4317.short\">sepsis<\/a>?<\/p>\n<p>Well, we can estimate this in a few ways. The simplest is using the 3\/n rule (if you&#8217;ve not seen it happen, then there&#8217;s still a 3\/n &#8211; 3\/100 chance in out example &#8211; that it will happen with 95% confidence). More sophisticated is the formal estimation of a binomial confidence interval (again, more can follow about this if we get any comments requesting it via the blog or twitter!). But the idea is the same &#8211; even when we don&#8217;t know, we can use what we do know to make an educated guess at it.<\/p>\n<p>Remember this when faced with new treatments, pathognmonic signs or prognotic certainties. You can know what you don&#8217;t.<\/p>\n<p>&nbsp;<!--TrendMD v2.4.8--><\/p>\n","protected":false},"excerpt":{"rendered":"<p>How you know about stuff you don&#8217;t know about is a fascinating philosophical, statistical and downright practical topic. There&#8217;s the issue of &#8216;unknown unknowns&#8217; &#8211; stuff you didn&#8217;t know you didn&#8217;t know &#8211; that can be frighteningly and sometimes dangerous. (How may of you know that failure to thrive is a common manifestation of a [&#8230;]<\/p>\n<p><a class=\"btn btn-secondary understrap-read-more-link\" href=\"https:\/\/blogs.bmj.com\/adc\/2013\/03\/06\/harms-safety-and-certainties\/\">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":[79],"tags":[],"class_list":["post-377","post","type-post","status-publish","format-standard","hentry","category-archimedes"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.4 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Harms, safety and certainties - 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\/2013\/03\/06\/harms-safety-and-certainties\/\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Harms, safety and certainties - ADC Online Blog\" \/>\n<meta property=\"og:description\" content=\"How you know about stuff you don&#8217;t know about is a fascinating philosophical, statistical and downright practical topic. There&#8217;s the issue of &#8216;unknown unknowns&#8217; &#8211; stuff you didn&#8217;t know you didn&#8217;t know &#8211; that can be frighteningly and sometimes dangerous. 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