Editing Blinded experiment (section)

===In medicine===
Blinding is considered essential in medicine,<ref>{{cite web|url=http://www.cebm.net/oxford-centre-evidence-based-medicine-levels-evidence-march-2009/|title=Oxford Centre for Evidence-based Medicine - Levels of Evidence (March 2009) - CEBM|date=11 June 2009|website=cebm.net|access-date=2 May 2018|url-status=live|archive-url=https://web.archive.org/web/20171026195451/http://www.cebm.net/oxford-centre-evidence-based-medicine-levels-evidence-march-2009/|archive-date=26 October 2017}}</ref> but is often difficult to achieve. For example, it is difficult to compare surgical and non-surgical interventions in blind trials. In some cases, [[sham surgery]] may be necessary for the blinding process. A good [[clinical protocol]] ensures that blinding is as effective as possible within ethical and practical constrains.

Studies of blinded pharmacological trials across widely varying domains find evidence of high levels of unblinding. Unblinding has been shown to affect both patients and clinicians. This evidence challenges the common assumption that blinding is highly effective in pharmacological trials. Unblinding has also been documented in clinical trials outside of pharmacology.<ref>{{cite journal |last1=JUL 2009 |first1=The Pharmaceutical Journal31 |title=An example of problems that arise from clinical trials and how to avoid them |journal=Pharmaceutical Journal |date=31 July 2009 |volume=283 |pages=129–130 |url=https://www.pharmaceutical-journal.com/opinion/comment/an-example-of-problems-that-arise-from-clinical-trials-and-how-to-avoid-them/10973550.article?firstPass=false |access-date=24 April 2019 |language=en}}</ref>

====Pain====

A 2018 [[meta-analysis]] found that assessment of blinding was reported in only 23 out of 408 randomized controlled trials for chronic pain (5.6%). The study concluded upon analysis of pooled data that the overall quality of the blinding was poor, and the blinding was "not successful." Additionally, both pharmaceutical sponsorship and the presence of side effects were associated with lower rates of reporting assessment of blinding.<ref>{{cite journal |last1=Colagiuri |first1=Ben |last2=Sharpe |first2=Louise |last3=Scott |first3=Amelia |title=The Blind Leading the Not-So-Blind: A Meta-Analysis of Blinding in Pharmacological Trials for Chronic Pain |journal=The Journal of Pain |volume=20 |issue=5 |pages=489–500 |date=September 2018 |doi=10.1016/j.jpain.2018.09.002 |pmid=30248448 |s2cid=52813251 |url=https://www.jpain.org/article/S1526-5900(18)30603-5/abstract |access-date=22 April 2019 |language=en |issn=1526-5900|doi-access=free }}</ref>

====Depression====

Studies have found evidence of extensive unblinding in [[antidepressant]] trials: at least three-quarters of patients were able to correctly guess their treatment assignment.<ref>{{cite journal |last1=Perlis |first1=Roy H. |last2=Ostacher |first2=Michael |last3=Fava |first3=Maurizio |last4=Nierenberg |first4=Andrew A. |last5=Sachs |first5=Gary S. |last6=Rosenbaum |first6=Jerrold F. |title=Assuring that double-blind is blind |journal=The American Journal of Psychiatry |date=2010 |volume=167 |issue=3 |pages=250–252 |doi=10.1176/appi.ajp.2009.09060820 |pmid=20194487 |s2cid=207628021 |issn=1535-7228}}</ref> Unblinding also occurs in clinicians.<ref>{{cite journal |last1=White |first1=K. |last2=Kando |first2=J. |last3=Park |first3=T. |last4=Waternaux |first4=C. |last5=Brown |first5=W. A. |title=Side effects and the "blindability" of clinical drug trials |journal=The American Journal of Psychiatry |date=December 1992 |volume=149 |issue=12 |pages=1730–1731 |doi=10.1176/ajp.149.12.1730 |pmid=1443253 |issn=0002-953X}}</ref> Better blinding of patients and clinicians reduces [[effect size]]. Researchers concluded that unblinding inflates effect size in antidepressant trials.<ref>{{cite journal |last1=Moncrieff |first1=Joanna |last2=Wessely |first2=Simon |last3=Hardy |first3=Rebecca |title=Meta-analysis of trials comparing antidepressants with active placebos |journal=British Journal of Psychiatry |date=2 January 2018 |volume=172 |issue=3 |pages=227–231 |doi=10.1192/bjp.172.3.227 |pmid=9614471 |s2cid=4975797 |issn=0007-1250}}</ref><ref>{{cite journal |last1=Greenberg |first1=RP |last2=Bornstein |first2=RF |last3=Greenberg |first3=MD |last4=Fisher |first4=S |title=A meta-analysis of antidepressant outcome under "blinder" conditions. |journal=Journal of Consulting and Clinical Psychology |date=October 1992 |volume=60 |issue=5 |pages=664–9; discussion 670–7 |doi=10.1037/0022-006X.60.5.664 |pmid=1401382 |issn=0022-006X}}</ref><ref>{{cite journal |last1=Moncrieff |first1=J |last2=Wessely |first2=S |last3=Hardy |first3=R |title=Active placebos versus antidepressants for depression. |journal=The Cochrane Database of Systematic Reviews |date=2004 |volume=2012 |issue=1 |pages=CD003012 |doi=10.1002/14651858.CD003012.pub2 |pmid=14974002 |issn=1469-493X|pmc=8407353 }}</ref> Some researchers believe that antidepressants are not effective for the treatment of depression and only outperform placebos due to [[observational error|systematic error]]. These researchers argue that antidepressants are just [[active placebo]]s.<ref name=Ioannidis2008>{{cite journal |last1=Ioannidis |first1=JP |title=Effectiveness of antidepressants: an evidence myth constructed from a thousand randomized trials? |journal=Philosophy, Ethics, and Humanities in Medicine |date=27 May 2008 |volume=3 |pages=14 |doi=10.1186/1747-5341-3-14 |pmid=18505564 |pmc=2412901 |issn=1747-5341 |doi-access=free }}</ref><ref name=Kirsch2014>{{cite journal |last1=Kirsch |first1=Irving |title=Antidepressants and the Placebo Effect |journal=Zeitschrift für Psychologie |date=2014 |volume=222 |issue=3 |pages=128–134 |doi=10.1027/2151-2604/a000176 |pmid=25279271 |pmc=4172306 |issn=2190-8370}}</ref>

====Acupuncture====

While the possibility of blinded trials on [[acupuncture]] is controversial, a 2003 review of 47 [[randomized controlled trial]]s found no fewer than four methods of blinding patients to acupuncture treatment: 1) superficial needling of true acupuncture points, 2) use of acupuncture points which are not indicated for the condition being treated, 3) insertion of needles outside of true acupuncture points, and 4) the use of placebo needles which are designed not to penetrate the skin. The authors concluded that there was "no clear association between type of sham intervention used and the results of the trials."<ref>{{cite journal |last1=Dincer |first1=F |last2=Linde |first2=K. |title=Sham interventions in randomized clinical trials of acupuncture—a review |journal=Complementary Therapies in Medicine |date=December 2003 |volume=11 |issue=4 |pages=235–242 |doi=10.1016/S0965-2299(03)00124-9 |pmid=15022656 |language=en}}</ref>

A 2018 study on acupuncture which used needles that did not penetrate the skin as a sham treatment found that 68% of patients and 83% of acupuncturists correctly identified their group allocation. The authors concluded that the blinding had failed, but that more advanced placebos may someday offer the possibility of well-blinded studies in acupuncture.<ref>{{cite journal |last1=Vase |first1=L |last2=Baram |first2=S |last3=Takakura |first3=N |last4=Takayama |first4=M |last5=Yajima |first5=H |last6=Kawase |first6=A |last7=Schuster |first7=L |last8=Kaptchuk |first8=TJ |last9=Schou |first9=S |last10=Jensen |first10=TS |last11=Zachariae |first11=R |last12=Svensson |first12=P |title=Can acupuncture treatment be double-blinded? An evaluation of double-blind acupuncture treatment of postoperative pain. |journal=PLOS ONE |date=2015 |volume=10 |issue=3 |pages=e0119612 |doi=10.1371/journal.pone.0119612 |pmid=25747157 |pmc=4352029 |issn=1932-6203|bibcode=2015PLoSO..1019612V |doi-access=free }}</ref>