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A problem of defining evidence as a fact is that fact cannot be false -facts are by definition true. This is not necessary the case with evidence - evidence can be false , as we often used in EBM ( eg " low quality of evidence" to indicate inconsistency with the truth). A separate issue is "public " vs. "private" evidence, or relation of definition of evidence to the methods employed. Some of this is discussed in the article I sent yesterday. Ben Djulbegovic Sent from my iPad ( please excuse typos & brevity) On Aug 23, 2012, at 4:48 AM, "Huw Llewelyn [hul2]" <[log in to unmask]<mailto:[log in to unmask]>> wrote: Hi Jon I can only re-iterate that evidence is a fact that is used to justify a prediction (which may or may not be verifiable later). The reliabiity of the facts making up the evidence have to be agreed with the listener or reader that one wishes to convince. The evidence must therefore be 'recognised' according to rules that promote some degree of reproducibility. The degree of reliability demanded of evidence varies between disciplines and individuals. Some will accept 'grey literature' especially if that is the only thing available but the certainty of any prediction will be low. If there are plenty of well documented, carefully observed, highly reproducible facts, then anything less may be rejected in that discipline. However, the uncritical may accept anything and those hostile to a prediction (eg because of COI) may say that even the best evidence that supports it is too unreliable to convince them! Huw ________________________________ From: Jon Brassey <[log in to unmask]<mailto:[log in to unmask]>> Date: Thu, 23 Aug 2012 08:00:44 +0100 To: Huw Llewelyn [hul2]<[log in to unmask]<mailto:[log in to unmask]>> Subject: Re: Definition of evidence Hi Huw, The fly in the ointment is how do non research-based documents fit into things e.g. grey literature, policy documents etc? While these are not research-based they are deemed 'evidence' (of a sort). So any defintion (for this particular role) needs to have a broader scope! BW jon On Wed, Aug 22, 2012 at 8:48 PM, Huw Llewelyn [hul2] <[log in to unmask]<mailto:[log in to unmask]>> wrote: Jon There are two issues here - what we see and what others report to us that they have seen. What we see for ourselves is a reliable fact and if it is used to make a prediction then it becomes evidence. When others report what they have seen we have to assess the probability that we would have seen the same thing if we had been there. In other words - What is the probability of replication? If this is high, then we might use the reported fact as evidence to make a prediction with a probability that is not quite as high as it would be if we had made the observation personally. Huw ________________________________ From: Tom Jefferson <[log in to unmask]<mailto:[log in to unmask]>> Sender: "Evidence based health (EBH)" <[log in to unmask]<mailto:[log in to unmask]>> Date: Wed, 22 Aug 2012 19:33:48 +0100 To: [log in to unmask]<mailto:[log in to unmask]><[log in to unmask]<mailto:[log in to unmask]>> ReplyTo: Tom Jefferson <[log in to unmask]<mailto:[log in to unmask]>> Subject: Re: Definition of evidence Jon, it depends whether you want to separate what is presented or reported from what really went on. These could be the same, either, or. Which do you mean? Best wishes, Tom. On 22 August 2012 18:11, Marilyn Mann <[log in to unmask]<mailto:[log in to unmask]>> wrote: Similar to the CDC definition: "What is the nature of the 'evidence' in EBM? We suggest a broad definition: any empirical observation about the apparent relation between events constitutes potential evidence." Guyatt et al. Introduction: The Philosophy of Evidence-Based Medicine. http://medicine.ucsf.edu/education/resed/articles/jama11_introduction.pdf Marilyn Mann ________________________________ From: "Juan Acuna" <[log in to unmask]<mailto:[log in to unmask]>> To: [log in to unmask]<mailto:[log in to unmask]> Sent: Wednesday, August 22, 2012 11:25:45 AM Subject: Re: Definition of evidence Hi Jon, This might help, in the context I believe you want to use the definition of EVIDENCE. It is the CDC definition: "evidence is a fact or datum which is used, or could be used, in making a decision or judgment or in solving a [health] problem" One reference: http://heapro.oxfordjournals.org/content/16/3/261.full Juan Juan M. Acuņa M.D., MSc., FACOG Associate Professor Human and Molecular Genetics, Obstetrics and Gynecology, and Clinical Epidemiology Florida International University Assistant Vice-President for Clinical and Community Research Director Division of Research and Information and Data Coordinating Center FIU Herbert Wertheim College of Medicine Guest Researcher, Centers for Disease Control and Prevention WHO-PAHO Collaborating Center 11200 SW 8th Street AHC2 - 474 Miami, FL 33199 Phone (305) 348 0676<tel:%28305%29%20348%200676> email: [log in to unmask]<mailto:[log in to unmask]><mailto:[log in to unmask]> ________________________________ From: Evidence based health (EBH) [[log in to unmask]<mailto:[log in to unmask]>] on behalf of Jon Brassey [[log in to unmask]<mailto:[log in to unmask]>] Sent: Wednesday, August 22, 2012 10:56 AM To: [log in to unmask]<mailto:[log in to unmask]> Subject: Definition of evidence Hi All, I've been asked to come up with the definition of 'evidence'. Some background it that it relates to an evidence service that will work with different types of 'evidence', such as primary research, secondary research, policy documents and gray literature. The service will do literatures searches, reviews etc. The definition is seen as important as we want to make a distinction between other services the organisations offers e.g. health intelligence! I imagine there's a definition out there somewhere! BW jon -- Dr Tom Jefferson www.attentiallebufale.it<http://www.attentiallebufale.it> -- Jon Brassey TRIP Database http://www.tripdatabase.com Find evidence fast