Randomized experiment: Difference between revisions

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[[Image:Flowchart of Phases of Parallel Randomized Trial - Modified from CONSORT 2010.png|thumb|250px|right|Flowchart of four phases (enrollment, intervention allocation, follow-up, and data analysis) of a parallel randomized trial of two groups, modified from the [[Consolidated Standards of Reporting Trials|CONSORT 2010 Statement]]<ref name="Schulz-2010">{{Cite journal | author = Schulz KF, Altman DG, Moher D; for the CONSORT Group |lastauthoramp=yes | title = CONSORT 2010 Statement: updated guidelines for reporting parallel group randomised trials | journal = BMJ | volume = 340 | pages = c332 | year = 2010 | doi = 10.1136/bmj.c332 | url = http://www.bmj.com/cgi/content/full/340/mar23_1/c332 | pmid = 20332509 | pmc = 2844940 }}</ref>]] In [[scientific method|science]], '''randomized experiments''' are the [[experiment]]s that allow the greatest reliability and validity of statistical estimates of treatment effects. Randomization-based inference is especially important in [[experimental design]] and in [[survey sampling]].

== Overview ==

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</ref>

Randomized experiments were institutionalized in psychology and education in the late eighteen-hundreds, following the invention of randomized experiments by [[Charles Sanders Peirce|C. S. Peirce]].<ref>{{cite journal| author=[[Charles Sanders Peirce]] and [[Joseph Jastrow]]| year=1885|title=On Small Differences in Sensation| journal=Memoirs of the National Academy of Sciences|volume=3|pages=73–83|url=http://psychclassics.yorku.ca/Peirce/small-diffs.htm}} http://psychclassics.yorku.ca/Peirce/small-diffs.htm</ref><ref>{{cite journal| doi=10.1086/354775| first=Ian |last=Hacking| authorlink=Ian Hacking | title=Telepathy: Origins of Randomization in Experimental Design|journal=[[Isis (journal)| Isis]]| issue=3| volume=79| date=September 1988 |pages=427–451| mr = 1013489| jstor=234674}}</ref><ref>{{cite journal| doi=10.1086/444032|author=[[Stephen M. Stigler]]|title=A Historical View of Statistical Concepts in Psychology and Educational Research| journal=American Journal of Education| volume=101| issue=1| date=November 1992|pages=60–70}}</ref><ref>{{cite journal|doi=10.1086/383850|author=Trudy Dehue|title=Deception, Efficiency, and Random Groups: Psychology and the Gradual Origination of the Random Group Design|journal=[[Isis (journal)|Isis]]| volume=88| issue=4| date=December 1997| pages=653–673|pmid=9519574}}</ref>

Outside of psychology and education, randomized experiments were popularized by [[R.A. Fisher]] in his book [[Statistical Methods for Research Workers]], which also introduced additional principles of experimental design.

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==Empirical evidence that randomization makes a difference==

Empirically differences between randomized and non-randomized studies,<ref>{{cite journal| doi=10.1002/14651858.MR000034.pub2|authorvauthors=Anglemyer A, Horvath HT, Bero L | title=Healthcare outcomes assessed with observational study designs compared with those assessed in randomized trials| journal=Cochrane Database Syst Rev|date=April 2014| pmid=24782322| volume=4| pages=MR000034}}</ref> and between adequately and inadequately randomized trials have been difficult to detect. <ref>{{cite journal| doi=10.1002/14651858.MR000012.pub3| vauthors=Odgaard-Jensen J, Vist G, etal |title=Randomisation to protect against selection bias in healthcare trials.| journal=Cochrane Database Syst Rev| date=April 2011|pmid=21491415|pages=MR000012}}</ref><ref>{{cite journal| doi=10.1186/1745-6215-15-480|authorvauthors=Howick J, Mebius A |title=In search of justification for the unpredictability paradox| journal=Trials| year=2014| volume=15| pmid=25490908| pages=480}}</ref>

==See also==

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{{Reflist}}

* {{cite book

|authorauthor1=Caliński, Tadeusz and |author2=Kageyama, Sanpei

|lastauthoramp=yes |title=Block designs: A Randomization approach, Volume '''I''': Analysis

|series=Lecture Notes in Statistics

|volume=150

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}}

* {{cite book

|authorauthor1=Caliński, Tadeusz and |author2=Kageyama, Sanpei

|lastauthoramp=yes |title=Block designs: A Randomization approach, Volume '''II''': Design

|series=Lecture Notes in Statistics

|volume=170