{"id":1546,"date":"2017-11-21T10:36:30","date_gmt":"2017-11-21T10:36:30","guid":{"rendered":"https:\/\/blogs.bmj.com\/bmjebmspotlight\/?p=1546"},"modified":"2018-07-01T17:53:22","modified_gmt":"2018-07-01T17:53:22","slug":"word-evidence-2-meta-analysis","status":"publish","type":"post","link":"https:\/\/blogs.bmj.com\/bmjebmspotlight\/2017\/11\/21\/word-evidence-2-meta-analysis\/","title":{"rendered":"A Word About Evidence: 2. Meta-analysis"},"content":{"rendered":"<p>&nbsp;<\/p>\n<p><em>The history of the statistical procedure called meta-analysis <a href=\"http:\/\/nutrigen.ph.ucla.edu\/files\/view\/epi-m258-spring-2012\/Glass.pdf\">begins<\/a> with GV Glass, who invented the word in the 1970s. But the history of the word itself begins long before that, with Aristotle.<\/em><\/p>\n<p style=\"text-align: right\">Jeff Aronson<\/p>\n<hr \/>\n<p><a href=\"https:\/\/blogs.bmj.com\/bmjebmspotlight\/files\/2017\/10\/aronson.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-1436 alignleft\" src=\"https:\/\/blogs.bmj.com\/bmjebmspotlight\/files\/2017\/10\/aronson-150x150.jpg\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/blogs.bmj.com\/bmjebmspotlight\/files\/2017\/10\/aronson-150x150.jpg 150w, https:\/\/blogs.bmj.com\/bmjebmspotlight\/files\/2017\/10\/aronson.jpg 160w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a>The Greek preposition \u03bc\u03b5\u03c4\u03b1 had several meanings, depending on whether it governed the accusative, genitive, or dative case. With the accusative it meant coming into or among, in pursuit of, or coming after in place or time; with the genitive it meant in the midst of, between, or in common with; and with the dative it meant in the company of or over and above. It was also used as a prefix, expressing such notions as sharing, being in the midst of, succession, pursuit, reversal, and (most commonly) change. Examples of the last include metabolism, metamorphosis, and metaplasia.<\/p>\n<p>In scientific English its uses include \u201cconsequent upon\u201d (as in the obsolete terms meta-arthritic, metapneumonic), anatomically \u201cbehind\u201d or \u201cbeyond\u201d (metabranchial, metacarpal, metaphysis), \u201ccoming later\u201d (metaphase, which comes after prophase in the cell cycle), or \u201cchanging\u201d (metachromasia, a property of materials that stain a different colour from the stain used). In geology meta\u2013 distinguishes various types of metamorphic processes. And chemists use it to differentiate certain metameric chemical compounds (for example metacresol, paracresol, orthocresol).<\/p>\n<p>In about 40 BC, some 280 years after Aristotle\u2019s death, <a href=\"https:\/\/plato.stanford.edu\/entries\/aristotle-commentators\/supplement.html\">Andronicus of Rhodes<\/a> catalogued his manuscripts in the order we know today. One set of papers, those dealing with natural science, he called <em>The Physics<\/em> (\u03c4\u1f70 \u03c6\u03c5\u03c3\u03b9\u03ba\u03ac), and the next set <em>The Metaphysics<\/em> (\u03c4\u1f70 \u03bc\u03b5\u03c4\u1f70 \u03c4\u1f70 \u03c6\u03c5\u03c3\u03b9\u03ba\u03ac), simply because it came after <em>The Physics<\/em>. However, because <em>The Metaphysics<\/em> dealt with what Aristotle called \u201cprimary philosophy\u201d or ontology, to be taught after natural philosophy, metaphysics came to mean \u201cthe science of that which transcends the physical\u201d.<\/p>\n<p>In the early 17th century meta\u2013 was used to designate any higher science (actual or hypothetical) that dealt with more fundamental problems than the original science itself. John Donne, for example, wrote about metatheology. However, this usage did not become really popular until the middle of the 19th century; examples include meta-ethics and meta-history (Table 1).<\/p>\n<p><strong>Table 1.<\/strong> Metasciences<\/p>\n<p><a href=\"https:\/\/blogs.bmj.com\/bmjebmspotlight\/files\/2017\/11\/table-1.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-1548\" src=\"https:\/\/blogs.bmj.com\/bmjebmspotlight\/files\/2017\/11\/table-1.png\" alt=\"\" width=\"928\" height=\"907\" srcset=\"https:\/\/blogs.bmj.com\/bmjebmspotlight\/files\/2017\/11\/table-1.png 928w, https:\/\/blogs.bmj.com\/bmjebmspotlight\/files\/2017\/11\/table-1-300x293.png 300w, https:\/\/blogs.bmj.com\/bmjebmspotlight\/files\/2017\/11\/table-1-768x751.png 768w\" sizes=\"auto, (max-width: 928px) 100vw, 928px\" \/><\/a><\/p>\n<p>Then, from about 1940, meta\u2013 came to designate concern with basic principles. A metacriterion is a criterion that defines criteria. A metatheorem is a theorem about theorems. A metalanguage is a language that supplies terms for analysing a language; a metametalanguage does the same for a metalanguage. [But a metaphysician is not a doctor\u2019s doctor.]<\/p>\n<p><em>Mantissa<\/em>, a medical novel by John Fowles, is metafiction; Francois Truffaut\u2019s film <em>La Nuit Amercaine <\/em>is metacinema, and several paintings by Magritte, notably <em>La Condition Humaine<\/em>, are meta-art, as are Jean Tinguely\u2019s machine-like sculptures, which he described as \u201cmetamechanical\u201d. In John Cage\u2019s metamusical piano piece, <em>4\u203233\u2033<\/em>, a pianist sits at the piano for the time indicated and does nothing, emphasizing the non-silent nature of silence; its 273 seconds represent \u2013273\u00b0C (absolute zero, or near enough).<\/p>\n<p><a href=\"https:\/\/www.scientificamerican.com\/article\/profile-of-martin-gardner\/\">Martin Gardner<\/a> stepped down from the <em>Scientific American<\/em> at the end of 1981, after contributing monthly articles for 25 years under the general title \u201cMathematical Games\u201d. He was <a href=\"https:\/\/www.scientificamerican.com\/article\/martin-gardner-hofstadter\/\">succeeded<\/a> by the computer scientist Douglas Hofstadter, who anagrammatically called his series \u201cMetamagical Themas\u201d. Hofstadter explained that \u201cMetamagical means \u2018going one level beyond magic\u2019. \u2026 The magical thing about magic is that what lies behind it is always <em>non<\/em>-magical \u2026 magic often lurks where few suspect it [and] seldom lurks where many suspect it.\u201d<\/p>\n<p>Much magic lurks in meta-analysis, analysis of analyses, preferably based on data from a systematic review, in which sets of previously published (or unpublished) data are themselves subjected as a whole to further statistical analysis.<\/p>\n<p>Some elide meta\u2013 with \u2013analysis, forming \u201cmetanalysis\u201d. David J Finney, in a 1995 <a href=\"https:\/\/www.ncbi.nlm.nih.gov\/pubmed\/7853052\">article<\/a> \u201cA statistician looks at met-analysis\u201d, cited the <em>Oxford English Dictionary<\/em> in support: \u201cMeta\u2013, before a vowel normally met\u2013\u201d. But the important word here is \u201cnormally\u201d, and in any case the dictionary\u2019s advice has since changed; it now says \u201cWhere the second element begins with a vowel, or h followed by a vowel, either the final <em>a<\/em> of meta\u2013 is lost, \u2026 or it is retained, with a hyphen being usual in the written form.\u201d \u201cMeta-analysis\u201d is preferable to \u201cmetanalysis\u201d, first because it avoids confusion with metanalysis (\u201cThe reinterpretation of the form of a word resulting in the creation of a new word\u201d), and secondly because it is used overwhelmingly more often; searching PubMed (Figure 1) I found 130\u00a0670 instances of meta-analysis as a textword (the earliest in 1977 by <a href=\"https:\/\/www.ncbi.nlm.nih.gov\/pubmed\/921048\">Smith and Glass<\/a>) compared with only 169 instances of metanalysis (the earliest in <a href=\"https:\/\/www.ncbi.nlm.nih.gov\/pubmed\/3290128\">1988<\/a>).<\/p>\n<figure id=\"attachment_1554\" aria-describedby=\"caption-attachment-1554\" style=\"width: 1308px\" class=\"wp-caption alignnone\"><a href=\"https:\/\/blogs.bmj.com\/bmjebmspotlight\/files\/2017\/11\/02.-Meta-analysis.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-1554 size-full\" src=\"https:\/\/blogs.bmj.com\/bmjebmspotlight\/files\/2017\/11\/02.-Meta-analysis.png\" alt=\"\" width=\"1308\" height=\"696\" srcset=\"https:\/\/blogs.bmj.com\/bmjebmspotlight\/files\/2017\/11\/02.-Meta-analysis.png 1308w, https:\/\/blogs.bmj.com\/bmjebmspotlight\/files\/2017\/11\/02.-Meta-analysis-300x160.png 300w, https:\/\/blogs.bmj.com\/bmjebmspotlight\/files\/2017\/11\/02.-Meta-analysis-768x409.png 768w, https:\/\/blogs.bmj.com\/bmjebmspotlight\/files\/2017\/11\/02.-Meta-analysis-1024x545.png 1024w\" sizes=\"auto, (max-width: 1308px) 100vw, 1308px\" \/><\/a><figcaption id=\"caption-attachment-1554\" class=\"wp-caption-text\">Figure 1. Numbers of publications with \u201cmeta-analysis\u201d as a textword in Pubmed<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>&#8220;Meta-analysis&#8221; first appeared in the <a href=\"https:\/\/www.jstor.org\/stable\/2182891?seq=1#page_scan_tab_contents\">philosophical literature<\/a> in 1953, meaning &#8220;Analysis of the grounds and assumptions on which a theory, explanation, or account is based.\u201d But its main use today is in its <a href=\"http:\/\/onlinelibrary.wiley.com\/doi\/10.1002\/9780470693926.fmatter\/pdf\">statistical sense<\/a>. As Gene Glass wrote \u201cThe term is a bit grand, but it is precise and apt.\u201d<\/p>\n<hr \/>\n<p><strong>Jeffrey Aronson<\/strong> is Associate Editor BMJ EBM, consultant physician, clinical pharmacologist and Fellow of CEBM<\/p>\n<p>Competing interests: none declared<!--TrendMD v2.4.8--><\/p>\n","protected":false},"excerpt":{"rendered":"<p>&nbsp; The history of the statistical procedure called meta-analysis begins with GV Glass, who invented the word in the 1970s. But the history of the word itself begins long before that, with Aristotle. Jeff Aronson The Greek preposition \u03bc\u03b5\u03c4\u03b1 had several meanings, depending on whether it governed the accusative, genitive, or dative case. With the [&#8230;]<\/p>\n<p><a class=\"btn btn-secondary understrap-read-more-link\" href=\"https:\/\/blogs.bmj.com\/bmjebmspotlight\/2017\/11\/21\/word-evidence-2-meta-analysis\/\">Read More&#8230;<\/a><\/p>\n","protected":false},"author":1,"featured_media":1493,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[14387,14381],"tags":[],"class_list":["post-1546","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-a-word-about-evidence","category-jeffrey-aronson"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.3 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>A Word About Evidence: 2. 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