Editing Blinded experiment (section)

===Premature unblinding===
Premature unblinding is any unblinding that occurs before the conclusion of a study. In contrast with post-study unblinding, premature unblinding is a source of bias. A [[code-break procedure]] dictates when a subject should be unblinded prematurely. A code-break procedure should only allow for unblinding in cases of emergency. Unblinding that occurs in compliance with code-break procedure is strictly documented and reported.<ref>{{cite journal |last1=Quittell |first1=Lynne M. |title=The Scientific and Social Implications of Unblinding a Study Subject |journal=The American Journal of Bioethics |date=3 October 2018 |volume=18 |issue=10 |pages=71–73 |doi=10.1080/15265161.2018.1513589 |pmid=30339067 |s2cid=53014880 |issn=1526-5161}}</ref>

Premature unblinding may also occur when a participant infers from experimental conditions information that has been masked to them. A common cause for unblinding is the presence of side effects (or effects) in the treatment group. In pharmacological trials, premature unblinding can be reduced with the use of an [[active placebo]], which conceals treatment allocation by ensuring the presence of side effects in both groups.<ref>{{cite journal |last1=Double |first1=D. B. |title=Placebo mania. Placebo controlled trials are needed to provide data on effectiveness of active treatment. |journal=BMJ: British Medical Journal |date=19 October 1996 |volume=313 |issue=7063 |pages=1008–9 |pmid=8892442 |pmc=2352320 |issn=0959-8138 |doi=10.1136/bmj.313.7063.1008b }}</ref> However, side effects are not the only cause of unblinding; any perceptible difference between the treatment and control groups can contribute to premature unblinding.{{cn|date=March 2023}}

A problem arises in the assessment of blinding because asking subjects to guess masked information may prompt them to try to infer that information. Researchers speculate that this may contribute to premature unblinding.<ref>{{cite journal |last1=Rees |first1=Judy R. |last2=Wade |first2=Timothy J. |last3=Levy |first3=Deborah A. |last4=Colford |first4=John M. |last5=Hilton |first5=Joan F. |title=Changes in beliefs identify unblinding in randomized controlled trials: a method to meet CONSORT guidelines |journal=Contemporary Clinical Trials |date=February 2005 |volume=26 |issue=1 |pages=25–37 |doi=10.1016/j.cct.2004.11.020 |pmid=15837450 |url=https://digitalcommons.unmc.edu/coph_epidem_articles/87 |url-access=subscription }}</ref> Furthermore, it has been reported that some subjects of clinical trials attempt to determine if they have received an active treatment by gathering information on social media and message boards. While researchers counsel patients not to use social media to discuss clinical trials, their accounts are not monitored. This behavior is believed to be a source of unblinding.<ref>{{cite web |last1=Ledford |first1=Heidi |title=A question of Control |url=https://www.nature.com/magazine-assets/d41586-018-07351-8/d41586-018-07351-8.pdf |publisher=Nature Magazine |access-date=24 April 2019}}</ref> CONSORT standards and [[good clinical practice]] guidelines recommend the reporting of all premature unblinding.<ref name=":0">{{cite journal |last1=Moher |first1=David |last2=Altman |first2=Douglas G. |last3=Schulz |first3=Kenneth F. |title=CONSORT 2010 Statement: updated guidelines for reporting parallel group randomised trials |journal=BMJ |date=24 March 2010 |volume=340 |pages=c332 |doi=10.1136/bmj.c332 |pmid=20332509 |pmc=2844940 |language=en |issn=0959-8138}}</ref><ref>{{cite web |title=E6(R2) Good Clinical Practice: Integrated Addendum to ICH E6(R1) Guidance for Industry |url=https://www.fda.gov/downloads/Drugs/Guidances/UCM464506.pdf#page=24 |archive-url=https://web.archive.org/web/20170202012038/http://www.fda.gov/downloads/Drugs/Guidances/UCM464506.pdf#page=24 |url-status=dead |archive-date=February 2, 2017 |website=fda.gov |access-date=21 April 2019|date = 2019-04-05}}</ref> In practice, unintentional unblinding is rarely reported.<ref name=Bello2014 />