Editing Blinded experiment (section)

== Background ==
=== Bias ===
A number of biases are present when a study is insufficiently blinded. Patient-reported outcomes can be different if the patient is not blinded to their treatment.<ref>{{cite journal |last1=Hróbjartsson |first1=A |last2=Emanuelsson |first2=F |last3=Skou Thomsen |first3=AS |last4=Hilden |first4=J |last5=Brorson |first5=S |title=Bias due to lack of patient blinding in clinical trials. A systematic review of trials randomizing patients to blind and nonblind sub-studies. |journal=International Journal of Epidemiology |date=August 2014 |volume=43 |issue=4 |pages=1272–83 |doi=10.1093/ije/dyu115 |pmid=24881045 |pmc=4258786 }}</ref> Likewise, failure to blind researchers results in [[observer bias]].<ref>{{cite journal |last1=Bello |first1=S |last2=Krogsbøll |first2=LT |last3=Gruber |first3=J |last4=Zhao |first4=ZJ |last5=Fischer |first5=D |last6=Hróbjartsson |first6=A |title=Lack of blinding of outcome assessors in animal model experiments implies risk of observer bias. |journal=Journal of Clinical Epidemiology |date=September 2014 |volume=67 |issue=9 |pages=973–83 |doi=10.1016/j.jclinepi.2014.04.008 |pmid=24972762 |doi-access=free }}</ref> Unblinded data analysts may favor an analysis that supports their existing beliefs ([[confirmation bias]]). These biases are typically the result of subconscious influences, and are present even when study participants believe they are not influenced by them.<ref name=Truth>{{cite journal |last1=MacCoun |first1=Robert |last2=Perlmutter |first2=Saul |title=Blind analysis: Hide results to seek the truth |journal=Nature |date=7 October 2015 |volume=526 |issue=7572 |pages=187–189 |doi=10.1038/526187a |pmid=26450040 |bibcode=2015Natur.526..187M |doi-access=free }}</ref>

=== Terminology ===
{{redirect-distinguish|Double blind|Double bind}}
In medical research, the terms ''single-blind'', ''double-blind'' and ''triple-blind'' are commonly used to describe blinding. These terms describe experiments in which (respectively) one, two, or three parties are blinded to some information. Most often, single-blind studies blind patients to their [[Treatment and control groups|treatment allocation]], double-blind studies blind both patients and researchers to treatment allocations, and triple-blinded studies blind patients, researcher, and some other third party (such as a monitoring committee) to treatment allocations. However, the meaning of these terms can vary from study to study.<ref name= Schulz2002>{{cite journal|vauthors=Schulz KF, Chalmers I, Altman DG|s2cid=34932997|date=February 2002|title=The landscape and lexicon of blinding in randomized trials|journal=Annals of Internal Medicine|volume=136|issue=3|pages=254–9|doi=10.7326/0003-4819-136-3-200202050-00022|pmid=11827510}}</ref>

[[CONSORT]] guidelines state that these terms should no longer be used because they are ambiguous. For instance, "double-blind" could mean that the data analysts and patients were blinded; or the patients and outcome assessors were blinded; or the patients and people offering the intervention were blinded, etc. The terms also fail to convey the information that was masked and the amount of unblinding that occurred. It is not sufficient to specify the number of parties that have been blinded. To describe an experiment's blinding, it is necessary to report ''who'' has been blinded to ''what'' information, and ''how well'' each blind succeeded.<ref>{{cite journal |last1=Moher |first1=David |last2=Hopewell |first2=Sally |last3=Schulz |first3=Kenneth F. |last4=Montori |first4=Victor |last5=Gøtzsche |first5=Peter C. |last6=Devereaux |first6=P. J. |last7=Elbourne |first7=Diana |last8=Egger |first8=Matthias |last9=Altman |first9=Douglas G. |title=CONSORT 2010 explanation and elaboration: updated guidelines for reporting parallel group randomised trials |journal=BMJ (Clinical Research Ed.) |date=23 March 2010 |volume=340 |pages=c869 |doi=10.1136/bmj.c869 |pmid=20332511 |pmc=2844943 |issn=1756-1833}}</ref>