Robert, the list below should give you a good start. This is a hugely
important issue. We find the majority of published trials to be at high
risk of bias and thus with a high likelihood of distorted results Best,
Mike

Wood L, Egger M, Gluud LL, Schulz KF, Jüni P, Altman DG, Gluud C, Martin RM,
Wood AJ, Sterne JA. Empirical evidence of bias in treatment effect
estimates in
controlled trials with different interventions and outcomes:
meta-epidemiological study. BMJ. 2008 Mar 15;336(7644):601-5. PMID:
18316340; PMCID: PMC2267990.

Lundh A et al. Quality of systematic reviews in pediatric oncology – A
systematic review. Cancer Treat Rev (2009), doi:10.1016/j.ctrv.2009.08.010

Hartling L. Risk of bias versus quality assessment of randomised
controlled trials: cross sectional study BMJ 2009;
339:b4012doi:10.1136/bmj.b4012

van Tulder MW, Suttorp M, Morton S, Bouter LM, Shekelle P. Empirical
evidence of an association between internal validity and effect size in
randomized controlled trials of low-back pain. Spine (Phila Pa 1976). 2009
Jul 15;34(16):1685-92. PubMed PMID: 19770609.

Tierney JF, Stewart LA. Investigating patient exclusion bias in
meta-analysis. Int J Epidemiol. 2005 Feb;34(1):79-87. Epub 2004 Nov 23.
PMID: 15561753

Jüni P, Altman DG and Egger M. Systematic reviews in health care:
Assessing the quality of controlled clinical trials. BMJ. 2001;323;42-46.
PMID: 11440947

Poolman RW, Struijs PA, Krips R, Sierevelt IN and others. Reporting of
outcomes in orthopaedic randomized trials: does blinding of outcome
assessors matter? J Bone Joint Surg Am. 2007 Mar;89(3):550-8.  PMID
17332104

Schulz KF, Chalmers I, Hayes RJ, Altman DG. Empirical evidence of bias.
Dimensions of methodological quality associated with estimates of of
treatment effects in controlled trials. JAMA 1995;273:408­12. PMID:
7823387

Kjaergard LL, John Villumsen J, Gluud C. Reported Methodologic Quality and
Discrepancies between Large and Small Randomized Trials in Meta-Analyses. 
Ann Intern Med. 2001;135:982-989. PMID 11730399

Jüni P, Altman DG and Egger M. Systematic reviews in health care:
Assessing the quality of controlled clinical trials. BMJ. 2001;323;42-46.
PMID: 11440947

Pildal J, Chan AW, Hrobjartsson A, Forfang E, and others. Comparison of
descriptions of allocation concealment in trial protocols and the
published reports: cohort study. BMJ. 2005 May 7;330(7499):1049. Epub 2005
Apr 7.l PMID: 15817527.


Egger M, Juni P, Bartlett C, Holenstein, and others. How important are
comprehensive literature searches and the assessment of trial quality in
systematic reviews? Empirical study. Health Technology Assessment 2003;
Vol.7: No.1. PMID: 12583822

Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C JAMA. 2007 Feb
28;297(8):842-57.Mortality in randomized trials of antioxidant supplements
for primary and secondary prevention: systematic review and
meta-analysis.PMID*: 17327526

Bangalore S, Wetterslev J, Pranesh S, Sawhney S, Gluud C, Messerli FH.
Perioperative β blockers in patients having non-cardiac surgery: a
meta-analysis. Lancet 2008; published online Nov 11. DOI:10.1016/ S0140
6736(08)61560-3.

MacLehose RR, Reeves BC, Harvey IM, Sheldon TA, and others. A systematic
review of comparisons of effect sizes derived from randomised and
non-randomised studies. Health Technol Assess. 2000;4(34):1-154. Review.
PMID: 11134917

Pocock SJ, Elbourne DR. Randomized trials or observational tribulations? N
Engl J Med. 2000;342:1907-1909.

O'Brien PC, Zhang D, Bailey KR. Semi-parametric and non-parametric methods
for clinical trials with incomplete data. Stat Med. 2005 Feb
15;24(3):341-58. Erratum in: Stat Med. 2005 Nov 15;24(21):3385.  PMID:
15547952

Carpenter, J, Kenward, M.  Guidelines for handling missing data in Social
Science Research.
www.lshtm.ac.uk/msu/missingdata/guidelines.pdf accessed (02/20/2008)

Gadbury GL, Coffey CS, Allison DB. Modern statistical methods for handling
missing repeated measurements in obesity trial data: beyond LOCF. Obes
Rev. 2003 Aug;4(3):175-84. PMID: 12916818

Shih W. Problems in dealing with missing data and informative censoring in
clinical trials. Curr Control Trials Cardiovasc Med. 2002 Jan 8;3(1):4.
PubMed PMID: 11985778; PubMed Central PMCID: PMC134476.

Wood AM, White IR, Thompson SG. Are missing outcome data adequately
handled? A review of published randomized controlled trials in major
medical journals. Clin Trials. 2004;1(4):368-76. Review. PubMed PMID:
16279275.

Woolley SB, Cardoni AA, Goethe JW. Last-observation-carried-forward
imputation method in clinical efficacy trials: review of 352
antidepressant studies. Pharmacotherapy. 2009 Dec;29(12):1408-16. Review.
PubMed PMID: 19947800.

Lachin JL. Statistical considerations in the intent-to-treat principle.
Control Clin Trials. 2000 Oct;21(5):526. PMID 11018568

Chalmers TC, Celano P, Sacks HS, Smith H Jr. Bias in treatment assignment
in controlled clinical trials. N Engl J Med. 1983 Dec 1;309(22):1358-61.
PMID: 6633598







>  I would appreciate it if list members might have references to pubs that
> document that effect size declines with improved research methodology.
>
>
>
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