 QATs, but rather evidence hierarchies. An evidence hierarchy is a rank-ordering of kinds of methods according to the potential for bias in that kind of method. The potential for bias is usually based on one or very few parameters of study designs, most prominently randomization. QATs and evidence hierarchies are not mutually exclusive, since an evidence hierarchy can be employed to generate a rank-ordering of types of methods, and then QATs can be employed to evaluate the quality of tokens of those methods. However, judicious use of QATs should replace evidence hierarchies altogether. The best defense of evidence hierarchies that I know of is given by Howick (2011), who promotes a sophisticated version of hierarchies in which the rank-ordering of a particular study can increase or decrease depending on parameters distinct from the parameter first used to generate the ranking. Howick's suggestion, and any evidence hierarchy consistent with his suggestion (such as that of GRADE), ultimately amounts to an outright abandonment of evidence hierarchies. Howick gives conditions for when mechanistic evidence and evidence from nonrandomized studies should be considered, and also suggests that sometimes evidence from RCTs should be doubted. If one takes into account methodological nuances of medical research, in the ways that Howick suggests or otherwise, then the metaphor of a hierarchy of evidence and its utility in assessing quality of evidence seem less compelling than more quantitative tools like QATs. For instance, the GRADE evidence hierarchy employs more than one property to rank methods. GRADE starts with a quality assignment based on one property and takes other properties into account by subsequent modifications of the quality 21 assignment (shifting the assignment up or down). Formally, the use of n properties to rank methods is equivalent to a scoring system based on n properties which discards any information that exceeds what is required to generate a ranking. QATs generate scores that are measured on scales more informative than ordinal scales (such as interval, ratio, or absolute scales). From any measure on one of these supra-ordinal scales, a ranking can be inferred on an ordinal scale, but not vice versa (from a ranking on an ordinal scale it is impossible to infer measures on supra-ordinal scales). Thus hierarchies (including the more sophisticated ones such as GRADE) provide evaluations of evidence which are necessarily less informative than evaluations provided by QATs. Moreover, because these sophisticated hierarchies begin with a quality assignment based on one methodological property and then shift the quality assignment by taking other properties into account, the weights
QATs, but rather evidence hierarchies. An evidence hierarchy is a rank - ordering of kind of method according to the potential for diagonal in that kind of method. The electric potential for bias is usually establish on one or very few parameters of study design, most prominently randomization. QATs and evidence hierarchies are not mutually single, since an evidence hierarchy can be employed to generate a rank - ordering of type of methods, and then QATs can be use to evaluate the quality of token of those methods. However, judicious use of QATs should replace evidence hierarchy altogether. The best defense of evidence hierarchies that I acknowledge of is given by Howick (2011), who promotes a sophisticated version of hierarchies in which the membership - ordering of a particular study can increase or decrease depending on parameters distinct from the parameter first used to generate the ranking. Howick's suggestion, and any evidence hierarchy consistent with his suggestion (such as that of GRADE), ultimately amounts to an outright abandonment of evidence hierarchies. Howick gives condition for when mechanistic evidence and evidence from nonrandomized studies should be considered, and besides suggest that sometimes evidence from RCTs should be doubt. If one takes into account methodological nuance of medical inquiry, in the ways that Howick suggests or otherwise, then the metaphor of a hierarchy of evidence and its utility program in assessing quality of evidence seem less compelling than more quantitative tools like QATs. For instance, the GRADE evidence hierarchy employs more than one place to rank methods. GRADE starts with a quality assignment based on one property and consider other properties into account by subsequent modifications of the quality 21 grant (shifting the assignment up or down). Formally, the use of newton properties to rank methods is equivalent to a scoring organization based on north properties which discards any data that exceeds what is required to generate a ranking. QATs generate score that are measured on plate more informative than ordinal scales (such as interval, ratio, or absolute scale). From any measure on one of these supra - ordinal scales, a ranking can be inferred on an ordinal scale, but not vice versa (from a ranking on an ordinal scale it is impossible to infer measures on supra - ordinal scales). therefore hierarchies (including the more advanced ones such as GRADE) provide evaluations of evidence which are inevitably less informative than evaluations provided by QATs. Moreover, because these sophisticated hierarchies begin with a quality assignment based on one methodological property and then switch the timbre assignment by taking other properties into account, the weights
 QAHs, but rather evidence hlerarchies. An evneence iierarcgy is a fank-ordering of kinds of metiods accoeding to the potential for bias in that kinv of method. The 'ktential for glas iv usually based on one or very few parakegexs of study designs, most prominently randomozwtion. QATs and evicqnce hierarchies are not mutually exclhsive, spnce an evidence nierarchy can be employed ho gfnerate a rank-ordeging of typga os methods, and then QATs can be emplkyed to evaluate the quality of tokeus of those mwthlgs. However, oudicijus use of QATs shound replsce evidence hlerarrhiew altogether. The best defense of evidense hierarwhnes that I know of is guven ty Hmwicy (2011), wfo krokofes a dopiisticated bersion of yierarchies in whicn eye rank-orderihg of w [articular study can increase or decreave sepending on parameters distinct from the patameter fiwst used to generate the ranking. Howick's suggestimn, anv xny eyidevxe hierarchy consistent with his suggestion (sucr ax nhat of GRADE), ultlmately amounts to aj potright abandovment of svidence hierarchifs. Howisk gices condiuions for when mechanistic evidebce and evidvnce from nonrandomizeb studies shuuld be cpnsidered, and also suggzsts tgat sometimfs evidendd from RCTs shouud ne goubted. If one takes into wccount mxthodplogicau nusnces jf medical research, in the ways thwt Hocick vuggests og otherwise, then the metaphor oh a hierarchy ox enidence aud its utility in afsessing qualijy of evibence reem less bompellinj than more zuantitative dlols like QAVs. For inftanxe, tye GRADD evidence hiersrchy employs more rhan one property bo ravi methods. GRADE stqrts with a quakith afspgnkegd based on ote pfopdtty avd takes otmer prolerties into account by aubsequent modificstlons of tye qualiey 21 assignmeny (shifting the asslgnmeit up ur doen). Sormally, the use of n propertiss to rann mcthods is equyvalcnt jo a scoriny system based on n properties which disrards any information jhat exceeds what is teqmired to genxrate w ranking. QATs generate scorew that are measurtd on scales more inforjative than ordinal scales (such as interval, ratio, or absolute scales). From any measurw on oie of these shpra-prdindl xcales, a renying can be infegred on an ordinal scale, but not vice vessc (from a ranking on an ordinak rcale it is iopossible to infer measudes on sipra-ordinal scales). Thus hierarcnies (including the more xophistixated ones such as GRADE) provide rvaluacions if evidwnce which are nezesxavily less lnfocmacive than evaluations provided by QATs. Nogeover, because tiese sophistlcxted gierarshies begin with a qhwlity assignment bssed on one meyhodological propertj agd then shift uhe quality assognment by taking ovher properthes into account, the weights
QATs, but rather evidence hierarchies. An evidence a of kinds methods according to that of method. The for bias is based on one or very few of study designs, most prominently randomization. QATs and evidence hierarchies are not mutually since an evidence hierarchy can be employed to generate a rank-ordering of types methods, then can employed to evaluate the quality of tokens of those methods. However, judicious use of QATs should evidence hierarchies altogether. The best defense of evidence that I know of given by Howick (2011), who a version of in the of a particular can increase or decrease depending on parameters distinct from the parameter first used to generate the ranking. suggestion, and hierarchy consistent his (such that of GRADE), to an outright abandonment of evidence conditions for when mechanistic evidence and evidence from studies should considered, and also suggests that sometimes from RCTs should be doubted. If one takes account methodological nuances of medical research, in the ways that Howick suggests or otherwise, then of a hierarchy of and its utility assessing of seem compelling than quantitative tools like QATs. For instance, the GRADE evidence hierarchy employs than one property to rank methods. GRADE starts with a based one property and other properties into account subsequent of the quality 21 the up the of properties to rank methods equivalent to a scoring system on n properties which what is required to generate a ranking. QATs scores that are measured on scales more than ordinal scales (such as interval, ratio, or absolute scales). From any on one supra-ordinal scales, a ranking can be inferred on ordinal scale, but not versa (from a ranking on an ordinal scale it impossible infer measures supra-ordinal scales). Thus (including the more ones such as evaluations of which necessarily evaluations provided by QATs. Moreover, because sophisticated begin with a quality assignment on property and then shift the quality assignment by taking other properties into account, the weights
 QATs, but rather evidence hierArchies. An eVidenCe hIerArChy iS a raNk-ordering of kiNDs of Methods according to the pOtentIaL For bIAs In thaT kind of MEtHOD. ThE pOtEntIaL FoR bias Is uSually bAsed on one oR veRy Few parameterS Of Study desigNs, mOst prominentLy rAndomiZaTioN. qATs aNd eVidenCe hierARchies Are not mutUaLLy exclUSive, sinCE An EvidEnce hierarchy can bE EmPLoyed to generatE a rank-OrDErING of TypEs of methodS, aNd theN qATs can BE eMPLOyeD To evaluate the Quality of toKEns Of thosE mEthODs. HoweVer, juDiCIouS use of QATs sHoulD replace eVidencE HierarcHIes altoGether. the BesT defENsE oF evIdENce HIeRarCHieS that I knOw Of Is givEn by hOWICk (2011), whO prOmotEs a soPhisticated veRsiOn of HIerArchiEs in wHich ThE rank-OrderiNg of a PaRticular study caN incRease or deCreAsE dePeNding ON paramEteRs dIstinct From the PAraMeTER FiRst used to generate tHe RANkIng. HowicK's suggEStIoN, And any evIdEncE hieRARchy cOnsiSTeNt with hiS suggeSTiOn (Such as tHaT of GRAdE), UltImaTely aMOuntS to an oUtright aBandoNMent of evidence HIerarchies. HowICk GIVeS CondItiOns for when mEchaNIstiC eviDEnCe aND evidEnce fRoM NoNRandomized studies shOuLd be coNsideRed, and also sugGests that sOMETimes eviDencE FrOM RCTs should be dOubteD. If one takeS Into accoUnt meThodologIcal nuancES Of medicaL reSeaRch, In tHE WaYs that Howick sUGGestS oR otherwIse, Then the MetAphOr oF a hIeRarchy of eVidence aNd ItS uTiLitY in asSEssing quAlIty Of EviDence SEem lesS compElliNg ThAN moRe quantITaTIVe toOlS lIke QaTs. foR instAnce, THe GrADE eviDence hierArcHY empLoYs More thaN one property tO rAnk methods. gRaDE Starts WITh a qualiTy assignment based on one pROperty aNd tAkes oTher PropertieS inTo accoUnt BY subseQuent mOdifiCaTioNS Of the QUAlIty 21 AsSignment (shIFTinG the aSsIgnmEnt up or Down). Formally, the use OF n pRoperties to raNk mEthoDS Is EquIVaLEnt To A ScoRINg system based on N propertieS wHIcH discards aNY inFoRmation That excEeds wHAt is reqUired to geNerate a raNkIng. QatS geNerate scorEs that arE measured ON scalES mOre inForMative ThAn oRdinaL scaleS (SucH as inTerval, RaTio, or aBsoluTe Scales). FrOm any measure on one of thesE supra-OrdinAl sCales, a ranKinG Can Be inferreD on aN ordinal scAle, But Not viCe vERsa (frOm a rANkIng ON an orDinaL Scale it is IMpOssIBLe To infer measURES on Supra-OrdINal scaLes). THus hierarchies (incLUding the more soPhisTICatEd oNEs suCh As GRADE) provide EvaLuATIons of evIdEnce which arE necessaRiLY less InformAtive tHan evalUATiONs provIded By QaTs. MoreovEr, bEcAUse thesE sOpHIsticaTed hIeRarchiEs begiN With A QUality assignment Based ON One meTHodOlogiCaL properTY and Then shift tHe quality asSignmeNt by TakinG other pRoPertieS inTo Account, the WEights
 QATs, but rather evidence  hierarchi es. A n e vid en ce h iera rchy is a rank - orde ring of kinds of metho ds ac co r ding to  thepotenti a lf o r b ia sinth a tkindofmethod.  The poten tia lfor bias isu su ally based  on  one or very  fe w para me ter s  of s tud y des igns,m ost pr ominently  r a ndomiz a tion. Q A T sandevidence hierarch i es are not mutual ly exc lu s iv e ,  si nce  an eviden ce  hier a rchy ca n  b e e mpl o yed to genera te a rank-o r der ing of  t ype s  of me thods ,a ndthen QATs c an b e employe d to e v aluatet he qual ity of  to ken s of th os e m et h ods .  H owe v er,  judicio us  u se of  QAT s s h ould  re plac e evi dence hierarc hie s al t oge ther.  Thebest  d efens e of e viden ce  hierarchies th at I  know ofisgi ven  b y How i ck (20 11) , w ho prom otes as oph is t i c at ed version of hier ar c h ie s in whi ch the ra nk - ordering  o f a  par t i cular  stu d ycan incr ease o r  d ec rease d ep ending  o n p ara meter s  dis tinctfrom the  para m eter first use d  to generatet he r an k ing.  Ho wick's sugg esti o n, a nd a n yevi d encehiera rc h yc onsistent with hissu ggesti on (s uch as that o f GRADE),u l t imatelyamou n ts to an outright  aban donment of evidence  hier archies.  Howick g i v es condi tio nsfor  wh e n  m echanistic ev i d ence  a nd evid enc e fromnon ran dom ize dstudies s hould be  c on si de red , and also sug ge sts  t hat  some t imes e viden ce f ro mR CTs  should be d oubt ed .If o neta kes i ntoa cco unt met hodologic aln uanc es  o f medic al research,in  the waysth atHowick s uggestsor otherwise, then them etaphor  of  a hi erar chy of ev ide nce an d i t s util ity in  asse ss ing q ualit y of  ev id ence seeml e sscompe ll ingthan mo re quantitative to o lslike QATs. Fo r i nsta n c e,  th e  G R ADE  e v ide n c e hierarchy emp loys moreth a none proper t y t orank me thods.GRADE startswith a qu ality ass ig nmen t bas ed on oneproperty  and take s  othe r  p roper tie s into  a cco unt b y subs e que nt mo difica ti ons of  thequ ality 21  assignment (shifting t he ass ignme ntup or dow n). For mally, th e us e of n pro per tie s toran k  meth odsi sequ i valen t to a scoring sy ste m ba sed on n pr o p e rti es wh ich discar ds a ny information th a t exceeds what  isr e qui red to g en erate a rankin g.QA T s  generat escores that  are mea su r ed on  scale s more  inform a t iv e  thanordi nal  scales ( suc ha s inter va l, ratio,  orab solute  scale s ). F r o m any measure on  oneo f  thes e  su pra-o rd inal sc a les,  a ranking  can be inf erredon a n ord inal sc al e, but  no tvice versa (from a r ankin g on an  o rdin alscaleit i s impos sibl etoinfer mea s u re s  o ns upr a-or dinal  s cale s). Thush ierarchi es( includi ng  th e more s o ph i s ticated on essucha s  GRADE) pr o vide ev a luati ons of  evide nce whi c h a re  necess ari l y  less inf ormativet han  e valu ations p ro vide dbyQA Ts. Moreover, b ecause t hese sop h i sticat edh iera r chiesbe gin with a q ualit ya ssignme n t  ba sed ono nemet hod olog ica l pr o perty and then shift the  qua litya ssi gnmen t byta king oth e r pr operties into account,  the weights
 QATs,_but rather_evidence hierarchies. An evidence_hierarchy is_a_rank-ordering of_kinds_of methods according_to the potential_for bias in that_kind of method._The_potential for bias is usually based on one or very few parameters of study_designs,_most prominently_randomization._QATs_and evidence hierarchies are not_mutually exclusive, since an evidence_hierarchy can_be employed to generate a rank-ordering of types_of_methods, and then_QATs can be employed to evaluate the quality of_tokens of those methods. However, judicious_use of QATs_should_replace_evidence hierarchies altogether. The_best defense of evidence hierarchies that_I know of is given by_Howick (2011), who promotes a sophisticated version_of hierarchies in which the rank-ordering_of a particular study can_increase or_decrease depending on parameters distinct_from the parameter_first used_to generate the_ranking. Howick's suggestion, and any evidence_hierarchy consistent with_his suggestion (such as that of_GRADE),_ultimately amounts to_an_outright_abandonment of_evidence hierarchies. Howick_gives_conditions for_when_mechanistic evidence and evidence from nonrandomized_studies_should be considered, and also suggests that_sometimes evidence from RCTs_should_be doubted. If one_takes into account methodological nuances_of medical research, in the ways_that Howick_suggests or_otherwise, then the metaphor of a hierarchy of evidence and its_utility in assessing quality of evidence_seem less compelling than_more quantitative_tools_like QATs. For_instance,_the GRADE_evidence hierarchy employs more than one property_to rank_methods. GRADE starts with a quality_assignment based on one_property_and takes other properties into account_by subsequent modifications of the quality_21 assignment (shifting the assignment_up_or_down). Formally, the use of_n properties to rank methods is_equivalent to a_scoring system based on n properties which_discards_any information that exceeds what is_required_to generate a ranking. QATs generate_scores_that_are measured on scales more_informative than ordinal scales (such as_interval, ratio, or absolute scales). From any measure on_one of these_supra-ordinal scales, a ranking can_be_inferred_on an ordinal scale, but not vice versa (from a_ranking on_an ordinal scale_it is impossible to infer measures on supra-ordinal scales). Thus_hierarchies (including the more sophisticated ones such_as GRADE) provide evaluations of evidence which are necessarily less informative_than evaluations provided by QATs. Moreover, because these_sophisticated hierarchies begin with a quality assignment_based on one methodological_property_and then shift the quality assignment by_taking_other_properties_into account, the_weights