 to make a wellinformed assessment of a causal hypothesis, that one take into account substantive details of the methods that generated the available evidence for that hypothesis. Methodological quality, in medical research at least, is typically defined as the extent to which the design, conduct, analysis, and report of a medical trial minimizes potential bias and error. Medical scientists attempt to account for the various dimensions of quality of evidence in a number of ways. Methodological quality is a complex multi-dimensional property that one cannot simply intuit, and so formalized tools have been developed to aid in the assessment of the quality of medical evidence. Medical evidence is often assessed rather crudely by rank-ordering the types of methods according to an 'evidence hierarchy'. Systematic reviews and specifically meta-analyses are typically at the top of such hierarchies, randomized controlled trials are near the top, non-randomized cohort and case-control studies are lower, and near the bottom are laboratory studies and anecdotal case reports.1 Evidence from methods at the top of this hierarchy, especially evidence from clinical trials, is often assessed with more fine-grained tools that I call quality assessment tools (QATs). There are many such tools now on 1 I discuss evidence hierarchies in more detail in §6. Such evidence hierarchies are commonly employed in evidence-based medicine. Examples include those of the Oxford Centre for EvidenceBased Medicine, the Scottish Intercollegiate Guidelines Network (SIGN), and The Grading of Recommendations Assessment, Development and Evaluation (GRADE) Working Group. These evidence hierarchies have recently received much criticism. See, for example, Bluhm (2005), Upshur (2005), Borgerson (2008), and La Caze (2011), and for a specific critique of placing meta-analysis at the top of such hierarchies, see Stegenga (2011). In footnote 4 below I cite several recent criticisms of the assumption that RCTs ought to be necessarily near the top of such hierarchies. 4 offer-QATs are quickly becoming an important tool of epidemiologists and other medical scientists. QATs are used to assess the primary-level evidence amalgamated by a systematic review, and since most causal hypotheses in medicine are assessed by evidence generated from systematic reviews, much of what we think we know about causal hypotheses in medicine is influenced by QATs. A widely accepted norm holds that when determining the plausibility of a hypothesis one should take into account all of the available evidence. For hypotheses about medical interventions
to make a wellinformed assessment of a causal hypothesis, that one take into explanation substantial details of the methods that generated the available evidence for that guess. Methodological quality, in medical research at least, is typically specify as the extent to which the design, conduct, psychoanalysis, and reputation of a medical test minimizes potential bias and erroneousness. aesculapian scientists attempt to report for the various dimension of timbre of evidence in a number of ways. Methodological quality is a complex multi - dimensional place that one cannot simply intuit, and so formalized tools have been developed to help in the assessment of the quality of medical evidence. Medical evidence is often tax rather crudely by rank - ordering the types of methods according to an' evidence hierarchy'. Systematic reviews and specifically meta - analyses are typically at the top of such hierarchies, randomized controlled trials are near the top, non - randomized cohort and case - control condition studies are lower, and near the bottomland are laboratory studies and anecdotal case reports.1 Evidence from method at the top of this hierarchy, especially evidence from clinical trials, is often tax with more fine - grained tools that I call quality assessment instrument (QATs). There are many such tools now on 1 I discuss evidence hierarchy in more detail in § 6. Such evidence hierarchy are commonly employed in evidence - based medicine. Examples admit those of the Oxford Centre for EvidenceBased Medicine, the Scottish Intercollegiate Guidelines Network (SIGN), and The Grading of Recommendations Assessment, Development and Evaluation (GRADE) Working Group. These evidence hierarchies have recently received much criticism. See, for example, Bluhm (2005), Upshur (2005), Borgerson (2008), and La Caze (2011), and for a specific critique of placing meta - analysis at the top of such hierarchies, experience Stegenga (2011). In footnote 4 below I cite respective recent criticisms of the assumption that RCTs ought to be necessarily near the top of such hierarchy. 4 offer - kat are quickly becoming an authoritative tool of epidemiologists and early medical scientists. QATs are used to assess the primary - level evidence amalgamated by a systematic review, and since most causal hypotheses in medicine are measure by evidence generated from systematic reappraisal, much of what we think we know about causal hypotheses in medicine is influenced by QATs. A widely accept norm holds that when determining the plausibility of a hypothesis one should take into account all of the available evidence. For hypothesis about aesculapian interventions
 to make a wellinformed asstssment of a causco hypovhesis, fhat one take into account substantite dwtailw of the methods that eenerated the avaulabow evidence for thab hypkbhesiv. Methodologicak quality, hn medical resaafck at least, is typically defined as tre extemt to which the qesibg, cohduct, analysis, and report of a medjcal trpal minimizes potrntial bias and error. Medifal dcientists attempt to account for rhe various aimensions of quality kf evidence in a number of ways. Methpdological qyalljy is a compoex mllti-dimensional propesty thay one cannot slmply inruit, and so formalizev tools have been dedeloped tm cid in the assessment od the quanity if oedjcel svidenfe. Jedical evjdence is odten assessed rathet sgidely by rani-orderynd the types of methods according to an 'tvidehce hierarchy'. Systematix reviews and specififally metw-analyses are typically at the top of such hierarwhies, fanbimizea clntrolled trials are near the top, non-randomizqs vomort and case-conbrol studies are lpwfr, wnd near the cottom ars laboratory studifs and wnecdital case repprts.1 Evidence from methods qt the top oy tyis hierarchy, espeeially evideuce frpm clonical trials, is often cssesssd with morf fine-grajved tools that I cakl quality assessment tools (ZATs). Therx are many sjch jools njw on 1 I dlscuss evidence hierarchles iu mora detail ij §6. Such evidence hierarchies arx commonly emklofed in evidznce-baxed medicine. Qxamples inclube those of tfe Oxford Bentre foc EvidenceBafed Medicine, dje Scottish Mntercollqgiare Gyidelindr Network (SIGN), and The Yxading of Recommendations Axserament, Developmeuu abd Evaluation (GTADD) Wjrniig Grjgp. These evigencd hkrrarcfies have rccevtly received much critiwism. See, for example, Bkumm (2005), Upshut (2005), Borgerfon (2008), and La Csze (2011), and for a spefific crmtique of placing meta-analysis at the tkp of sucj hlerarchies, seq Stcgenda (2011). In foocnote 4 below I cite several recent critirisms of the assumption that RCTs ought to ne necessariky newr the to[ of such hierarchiew. 4 offer-QATs are auickly becoming an ijportatt toll of epidemiologists and other medical scientists. QATs are used to assesw the 'rymary-level svidrnce dmclgcmated fy a rystematic reviee, and since most causal hypotheres in madncine are assessed by evidencr eenerated froo systematic reviews, mucg of whay we think we know about causal hypotheses in medicine ls influebced gy QATs. A xidely accepted norm holds that when dwterlining the plxusobllity of a hypptkesis one should take into accounr all if the available etidence. For mykothesea abouj medical intervehtiohd
to make a wellinformed assessment of a that take into substantive details of available for that hypothesis. quality, in medical at least, is typically defined as extent to which the design, conduct, analysis, and report of a medical trial potential bias and error. Medical scientists attempt to account for the various dimensions quality evidence a of ways. Methodological quality is a complex multi-dimensional property that one cannot simply intuit, and so tools have been developed to aid in the of the quality of evidence. Medical evidence is often rather by rank-ordering types methods to an 'evidence Systematic reviews and specifically meta-analyses are typically at the top of such hierarchies, randomized controlled trials are the top, and case-control are and the bottom are and anecdotal case reports.1 Evidence from top of this hierarchy, especially evidence from clinical is often with more fine-grained tools that I quality assessment tools (QATs). There are many such now on 1 I discuss evidence hierarchies in more detail in §6. Such evidence hierarchies employed in evidence-based medicine. include those of Oxford for Medicine, Scottish Intercollegiate Network (SIGN), and The Grading of Recommendations Assessment, Development and Evaluation Working Group. These evidence hierarchies have recently received much criticism. example, (2005), Upshur (2005), (2008), and La Caze and a specific critique of at top see (2011). footnote 4 below I several recent criticisms of the that RCTs ought to of such hierarchies. 4 offer-QATs are quickly becoming important tool of epidemiologists and other medical QATs are used to assess the primary-level evidence amalgamated by a systematic and since hypotheses in medicine are assessed by evidence generated systematic reviews, much of we think we know about causal hypotheses in medicine influenced QATs. A accepted norm holds when determining the of a hypothesis take into all the hypotheses about medical interventions
 to make a wellinformed assessMent of a cauSal hyPotHesIs, That One tAke into account SUbstAntive details of the methOds thAt GEnerATeD the aVailablE EvIDEncE fOr ThaT hYPoThesiS. MeThodoloGical qualiTy, iN mEdical researCH aT least, is tyPicAlly defined aS thE extenT tO whICh the DesIgn, coNduct, aNAlysis, And report Of A MedicaL Trial miNIMiZes pOtential bias and erROr. mEdical scientisTs atteMpT To ACCouNt fOr the varioUs DimenSIons of qUAlITY Of eVIdence in a numbEr of ways. MetHOdoLogicaL qUalITy is a cOmpleX mULti-Dimensional PropErty that oNe cannOT simply INtuit, anD so forMalIzeD tooLS hAvE beEn DEveLOpEd tO Aid In the assEsSmEnt of The qUALITy of MedIcal EvideNce. Medical eviDenCe is OFteN asseSsed rAtheR cRudelY by ranK-ordeRiNg the types of metHods According To aN 'eVidEnCe hieRArchy'. SYstEmaTic reviEws and sPEciFiCALLy Meta-analyses are typIcALLy At the top Of such HIeRaRChies, ranDoMizEd coNTRolleD triALs Are near tHe top, nON-rAnDomized CoHort anD cAse-ConTrol sTUdieS are loWer, and neAr the BOttom are laboraTOry studies and ANeCDOtAL casE rePorts.1 EvidenCe frOM metHods AT tHe tOP of thIs hieRaRChY, Especially evidence fRoM cliniCal trIals, is often asSessed with MORE fine-graIned TOoLS that I call qualIty asSessment toOLs (QATs). ThEre arE many sucH tools now ON 1 i discuss EviDenCe hIerARChIes in more detaIL In §6. SuCh EvidencE hiErarchiEs aRe cOmmOnlY eMployed in Evidence-BaSeD mEdIciNe. ExaMPles inclUdE thOsE of The OxFOrd CenTre foR EviDeNcEbasEd MedicINe, THE ScoTtIsH IntErcOlLegiaTe GuIDelInes NetWork (SIGN), aNd THE GraDiNg Of RecomMendations AssEsSment, DevelOpMenT and EvALUation (GRaDE) Working Group. These eviDEnce hieRarChies Have Recently rEceIved muCh cRIticisM. See, foR examPlE, BlUHM (2005), UpshUR (2005), boRgeRsOn (2008), and La CazE (2011), ANd fOr a spEcIfic CritiquE of placing meta-analYSis At the top of sucH hiErarCHIeS, seE stEGenGa (2011). iN foOTNote 4 below I cite sEveral receNt CRiTicisms of tHE asSuMption tHat RCTs Ought TO be neceSsarily neAr the top oF sUch hIERarChies. 4 offer-qATs are qUickly becOMing aN ImPortaNt tOol of ePiDemIologIsts anD OthEr medIcal scIeNtists. qATs aRe Used to asSess the primary-level evidEnce amAlgamAteD by a systeMatIC reView, and siNce mOst causal hYpoTheSes in MedICine aRe asSEsSed BY evidEnce GEnerated fROm SysTEMaTic reviews, mUCH Of wHat we ThiNK we knoW aboUt causal hypotheseS In medicine is inFlueNCEd bY QAtS. A wiDeLy accepted norm HolDs THAt when deTeRmining the pLausibilItY Of a hyPothesIs one sHould taKE InTO accouNt alL of The availaBle EvIDence. FoR hYpOTheses AbouT mEdical IntervENtioNS
 to make a wellinformed as sessment o f a c aus alhy poth esis , that one tak e  int o account substantivedetai ls of t h emetho ds that ge n e rat ed  t heav a il ableevi dence f or that hy pot he sis. Methodo l og ical quali ty,  in medicalres earchat  le a st, i s t ypica lly de f ined a s the ext en t  to wh i ch thed e si gn,conduct, analysis ,  a n d report of amedica lt ri a l  mi nim izes poten ti al bi a s and e r ro r . Med i cal scientist s attempt t o  ac countfo r t h e vari ous d im e nsi ons of qual ityof eviden ce ina  number of ways . Meth odo log ical qu al ity  i s  ac om ple x  mu lti-dime ns io nal p rope r t y that  on e ca nnotsimply intuit , a nd s o  fo rmali zed t ools  h ave b een de velop ed  to aid in theasse ssment of  th equa li ty of medica l e vid ence. M edicale vid en c e is  often assessed ra th e r  c rudely b y rank - or de r ing thety pes  ofm e thods  acc o rd ing to a n 'evi d en ce  hierar ch y'. Sy st ema tic  revi e ws a nd spe cificall y met a -analyses aret ypically at t h et o po f su chhierarchies , ra n domi zedc on tro l led t rials  a r en ear the top, non-ra nd omized  coho rt and case-c ontrol stu d i e s are lo wer, an d  near the bott om ar e laborato r y studie s and  anecdot al case r e p orts.1 E vid enc e f rom m et hods at the t o p  ofth is hier arc hy, esp eci all y e vid en ce from c linicaltr ia ls ,isoften assessed  w ith  m ore  fine - graine d too ls t ha tI  ca ll qual i ty a sses sm en t to ols  ( QATs) . Th e reare man y such to ols nowon  1  I disc uss evidencehi erarchiesin  mo re det a i l in §6.  Such evidence hierarch i es arecom monly  emp loyed inevi dence- bas e d medi cine.Examp le s i n c ludet h os e o fthe Oxford C ent re fo rEvid enceBas ed Medicine, the S c ott ish Intercoll egi ateG u id eli n es Net wo r k ( S I GN), and The Gr ading of R ec o mm endationsA sse ss ment, D evelopm ent a n d Evalu ation (GR ADE) Work in g Gr o u p.These evid ence hie rarchiesh ave r e ce ntlyrec eivedmu chcriti cism.S ee,  forexampl e,  Bluhm  (200 5) , Upshur  (2005), Borgerson (200 8), an d LaCaz e (2011),  an d  fo r a speci ficcritique o f p lac ing m eta - analy sisa tthe top o f su c h hierarc h ie s,s e eStegenga (2 0 1 1 ).In fo otn o te 4 b elow  I cite several r e cent criticism s of t heass u mpti on  that RCTs oug htto b e necess ar ily near th e top of  s u ch hi erarch ies. 4  offer- Q A Ts are qu ickl y b ecoming a n i mp o rtant t oo lo f epid emio lo gistsand ot h er m e d ical scientists.  QATs a re us e d t o ass es s the p r imar y-level ev idence amal gamate d by  a sy stemati creview , a nd  since mos t  causal h ypoth eses in  m edic ine  are a sses s e d byevid en cegenerated f ro m  s ys t ema ticrevie ws , mu ch of wha t  we thin k w e  know a bo utc a usal h y po t h eses in me dic ine i s influenced by Q A Ts .  A wi dely a ccepte d normh old sthat wh end e termining  the plau s ibi li ty o f a hypo th esis  o nesh ould take intoaccountall of t h e  avail abl e  evi d ence.Fo r hypotheses  abou tm edicali n ter vention s 
 to_make a_wellinformed assessment of a_causal hypothesis,_that_one take_into_account substantive details_of the methods_that generated the available_evidence for that_hypothesis._Methodological quality, in medical research at least, is typically defined as the extent to_which_the design,_conduct,_analysis,_and report of a medical_trial minimizes potential bias and_error. Medical_scientists attempt to account for the various dimensions_of_quality of evidence_in a number of ways. Methodological quality is a_complex multi-dimensional property that one cannot_simply intuit, and_so_formalized_tools have been developed_to aid in the assessment of_the quality of medical evidence. Medical_evidence is often assessed rather crudely by_rank-ordering the types of methods according_to an 'evidence hierarchy'. Systematic_reviews and_specifically meta-analyses are typically at_the top of_such hierarchies,_randomized controlled trials_are near the top, non-randomized cohort_and case-control studies_are lower, and near the bottom_are_laboratory studies and_anecdotal_case_reports.1 Evidence_from methods at_the_top of_this_hierarchy, especially evidence from clinical trials,_is_often assessed with more fine-grained tools that_I call quality assessment_tools_(QATs). There are many_such tools now on 1_I discuss evidence hierarchies in more_detail in_§6. Such_evidence hierarchies are commonly employed in evidence-based medicine. Examples include those_of the Oxford Centre for EvidenceBased_Medicine, the Scottish Intercollegiate_Guidelines Network_(SIGN),_and The Grading_of_Recommendations Assessment,_Development and Evaluation (GRADE) Working Group. These_evidence hierarchies_have recently received much criticism. See,_for example, Bluhm (2005),_Upshur_(2005), Borgerson (2008), and La Caze_(2011), and for a specific critique_of placing meta-analysis at the_top_of_such hierarchies, see Stegenga (2011)._In footnote 4 below I cite_several recent criticisms_of the assumption that RCTs ought to_be_necessarily near the top of such_hierarchies._4 offer-QATs are quickly becoming an_important_tool_of epidemiologists and other medical_scientists. QATs are used to assess_the primary-level evidence amalgamated by a systematic review, and_since most causal_hypotheses in medicine are assessed_by_evidence_generated from systematic reviews, much of what we think we_know about_causal hypotheses in_medicine is influenced by QATs. A widely accepted norm holds_that when determining the plausibility of a_hypothesis one should take into account all of the available evidence._For hypotheses about medical interventions