Evidence map›Paper›PMID 29331519›Full record

ArticleSocial science & medicine (1982)2018

Understanding and misunderstanding randomized controlled trials.

Angus Deaton, Nancy Cartwright

Abstract read
PubMed Full text at PMC Publisher
In one paragraph

Article in Social science & medicine (1982), 2018. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 339 papers, 16 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
339citing papers in PubMed, 16 pooled it
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

339 citing papers in PubMed, 16 syntheses or guidelines pooled it.

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  16. Effectiveness of psychoeducation intervention among women with gynecological cancer: a systematic review and meta-analysis of randomized controlled trials.Supportive care in cancer : official journal of the Multinational Association of Supportive Care in Cancer · 2022
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279 more citing papers are in PubMed but not listed here.

4 · The record

Corrections and comments

5 · Who and what money

Authors and funding

2 authors.

Angus DeatonPrinceton University, USA; National Bureau of Economic Research, USA; University of Southern California, USA. Electronic address: deaton@princeton.edu.
Nancy CartwrightDurham University, England; UC San Diego, USA.

Funding

Understanding and Improving Healthcare Decision-Making and Outcomes for People Living with Alzheimer's Disease and Related DementiasP01AG005842 · NIA · NATIONAL BUREAU OF ECONOMIC RESEARCH · PI KOSALI ILAYPERUMA SIMON · 1986 to 2026
$56.5M
Scientific CoreP30AG024928 · NIA · PRINCETON UNIVERSITY · PI CURRIE, JANET M. · 2004 to 2018
$5.2M
Increasing Midlife Mortality and Morbidity in White Americans in the 21st CenturyR01AG053396 · NIA · NATIONAL BUREAU OF ECONOMIC RESEARCH · PI DEATON, ANGUS S. · 2016 to 2020
$1.1M
Dimensions of Subjective Well-Being: Aging, Religiosity, and AdaptationR01AG040629 · NIA · NATIONAL BUREAU OF ECONOMIC RESEARCH · PI DEATON, ANGUS S. · 2011 to 2015
$1.0M
NIA NIH HHS P01 AG005842NIA NIH HHS P30 AG024928NIA NIH HHS R01 AG040629NIA NIH HHS R01 AG053396
6 · The paper itself

Abstract

Randomized Controlled Trials (RCTs) are increasingly popular in the social sciences, not only in medicine. We argue that the lay public, and sometimes researchers, put too much trust in RCTs over other methods of investigation. Contrary to frequent claims in the applied literature, randomization does not equalize everything other than the treatment in the treatment and control groups, it does not automatically deliver a precise estimate of the average treatment effect (ATE), and it does not relieve us of the need to think about (observed or unobserved) covariates. Finding out whether an estimate was generated by chance is more difficult than commonly believed. At best, an RCT yields an unbiased estimate, but this property is of limited practical value. Even then, estimates apply only to the sample selected for the trial, often no more than a convenience sample, and justification is required to extend the results to other groups, including any population to which the trial sample belongs, or to any individual, including an individual in the trial. Demanding 'external validity' is unhelpful because it expects too much of an RCT while undervaluing its potential contribution. RCTs do indeed require minimal assumptions and can operate with little prior knowledge. This is an advantage when persuading distrustful audiences, but it is a disadvantage for cumulative scientific progress, where prior knowledge should be built upon, not discarded. RCTs can play a role in building scientific knowledge and useful predictions but they can only do so as part of a cumulative program, combining with other methods, including conceptual and theoretical development, to discover not 'what works', but 'why things work'.

Indexed as

Randomized Controlled Trials as TopicBiasComprehensionHumansBalanceBiasEconomic developmentExternal validityHealthPrecisionRCTsTransportation of results

Identifiers

PMID29331519
PMCPMC6019115

What OpenQuestion holds

Textmetadata
LicenceTDM
Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.