Discrepancies in sample size calculations and data analyses reported in randomised trials: comparison of publications with protocols
Open accessAbstract
OBJECTIVE: To evaluate how often sample size calculations and methods of statistical analysis are pre-specified or changed in randomised trials. DESIGN: Retrospective cohort study. Data source Protocols and journal publications of published randomised parallel group trials initially approved in 1994-5 by the scientific-ethics committees for Copenhagen and Frederiksberg, Denmark (n=70). MAIN OUTCOME MEASURE: Proportion of protocols and publications that did not provide key information about sample size calculations and statistical methods; proportion of trials with discrepancies between information presented in the protocol and the publication. RESULTS: Only 11/62 trials described existing sample size calculations fully and consistently in both the protocol and the publication. The method of handling protocol deviations was described in 37 protocols and 43 publications. The method of handling missing data was described in 16 protocols and 49 publications. 39/49 protocols and 42/43 publications reported the statistical test used to analyse primary outcome measures. Unacknowledged discrepancies between protocols and publications were found for sample size calculations (18/34 trials), methods of handling protocol deviations (19/43) and missing data (39/49), primary outcome analyses (25/42), subgroup analyses (25/25), and adjusted analyses (23/28). Interim analyses were described in 13 protocols but mentioned in only five corresponding publications. CONCLUSION: When reported in publications, sample size calculations and statistical methods were often explicitly discrepant with the protocol or not pre-specified. Such amendments were rarely acknowledged in the trial publication. The reliability of trial reports cannot be assessed without having access to the full protocols.
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Integrity signals
Registry
Cites
Statistics
Claims the paper makes
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
The interpretation of trial results in published reports is not always consistent with the prespecified conceptual framework.
“In addition, the interpretation of trial results in published reports is not always consistent with the prespecified conceptual framework,198 199 200 especially among reports claiming post hoc equivalence based on a failure to show superiority, rather than on a specific test of equivalence.198”
From SPIRIT 2025 explanation and elaboration: updated guideline for protocols of randomised trials (2025) · cites this paper as [200]
Among randomised trial protocols that describe a sample size calculation, studies often do not state all components necessary to understand and reproduce the sample size (including the derivation of the target difference and the source of estimated values).
“Among randomised trial protocols that describe a sample size calculation, studies often do not state all components necessary to understand and reproduce the sample size (including the derivation of the target difference and the source of estimated values).200 297”
From SPIRIT 2025 explanation and elaboration: updated guideline for protocols of randomised trials (2025) · cites this paper as [200]
These substantive modifications are rarely acknowledged in the final trial reports.
“These substantive modifications are rarely acknowledged in the final trial reports.200 249 250 480”
From SPIRIT 2025 explanation and elaboration: updated guideline for protocols of randomised trials (2025) · cites this paper as [200]
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
The self-check needs the paper’s full text.
Cites
Moher, D., Schulz, K. F., & Altman, D. G. (2001) · The Lancet · doi:10.1016/s0140-6736(00)04337-3 · Cited by 5,373 · see citing works
Self-citationThe Revised CONSORT Statement for Reporting Randomized Trials: Explanation and Elaboration
Altman, D. G., Schulz, K. F., Moher, D., Egger, M., Davidoff, F., Elbourne, D., Gøtzsche, P. C., Lang, T., & for the CONSORT Group (2001) · Annals of Internal Medicine · doi:10.7326/0003-4819-134-8-200104170-00012 · Cited by 3,835 · see citing works
Self-citationMoher, D., Schulz, K. F., & Altman, D. G. (2001) · BMC Medical Research Methodology · doi:10.1186/1471-2288-1-2 · Cited by 2,755 · see citing works
Self-citationSelective publication of antidepressant trials and its influence on apparent efficacy
Turner, E. H., Matthews, A. M., Linardatos, E., Tell, R. A., & Rosenthal, R. (2008) · New England Journal of Medicine · doi:10.1056/nejmsa065779 · Cited by 2,435 · see citing works
What is meant by intention to treat analysis? Survey of published randomised controlled trials
Hollis, S., & Campbell, F. (1999) · BMJ · doi:10.1136/bmj.319.7211.670 · Cited by 2,160 · see citing works
Chan, A.-W., Hróbjartsson, A., Haahr, M. T., Gøtzsche, P. C., & Altman, D. G. (2004) · JAMA · doi:10.1001/jama.291.20.2457 · Cited by 1,845 · see citing works
Self-citationSystematic Review of the Empirical Evidence of Study Publication Bias and Outcome Reporting Bias
Dwan, K., Altman, D. G., Arnaiz, J. A., Bloom, J., Chan, A.-W., Cronin, E., Decullier, E., Easterbrook, P. J., Von Elm, E., Gamble, C., et al. (2008) · PLoS ONE · doi:10.1371/journal.pone.0003081 · Cited by 1,546 · see citing works
Self-citationSubgroup analysis and other (mis)uses of baseline data in clinical trials
Assmann, S. F., Pocock, S. J., Enos, L. E., & Kasten, L. E. (2000) · The Lancet · doi:10.1016/s0140-6736(00)02039-0 · Cited by 1,167 · see citing works
Subgroup analysis in randomised controlled trials: importance, indications, and interpretation
Rothwell, P. M. (2005) · The Lancet · doi:10.1016/s0140-6736(05)17709-5 · Cited by 942 · see citing works
Post-randomisation exclusions: the intention to treat principle and excluding patients from analysis
Fergusson, D., Aaron, S. D., Guyatt, G., & Hébert, P. (2002) · BMJ · doi:10.1136/bmj.325.7365.652 · Cited by 708 · see citing works
Statistical Considerations in the Intent-to-Treat Principle
Lachin, J. M. (2000) · Controlled Clinical Trials · doi:10.1016/s0197-2456(00)00046-5 · Cited by 652 · see citing works
Melander, H., Ahlqvist-Rastad, J., Meijer, G., & Beermann, B. (2003) · BMJ · doi:10.1136/bmj.326.7400.1171 · Cited by 626 · see citing works
Statistical Power, Sample Size, and Their Reporting in Randomized Controlled Trials
Moher, D. (1994) · JAMA: The Journal of the American Medical Association · doi:10.1001/jama.1994.03520020048013 · Cited by 608 · see citing works
Brookes, S. T., Whitley, E., Peters, T. J., Mulheran, P. A., Egger, M., & Davey Smith, G. (2001) · Health Technology Assessment · doi:10.3310/hta5330 · Cited by 580 · see citing works
Sample size calculations in randomised trials: mandatory and mystical
Schulz, K. F., & Grimes, D. A. (2005) · The Lancet · doi:10.1016/s0140-6736(05)61034-3 · Cited by 549 · see citing works
The Challenge of Subgroup Analyses — Reporting without Distorting
Lagakos, S. W. (2006) · New England Journal of Medicine · doi:10.1056/nejmp068070 · Cited by 504 · see citing works
Publication and Related Biases
Song, F., Eastwood, A. J., Gilbody, S. M., Duley, L., & Sutton, A. J. (2001) · SAGE Publications Ltd eBooks · doi:10.4135/9781848608344.n21 · Cited by 470 · see citing works
Analyzing incomplete longitudinal clinical trial data
Molenberghs, G. (2004) · Biostatistics · doi:10.1093/biostatistics/5.3.445 · Cited by 463 · see citing works
Outcome reporting bias in randomized trials funded by the Canadian Institutes of Health Research
Chan, A.-W. (2004) · Canadian Medical Association Journal · doi:10.1503/cmaj.1041086 · Cited by 444 · see citing works
Self-citationPublication and related biases.
Song, Eastwood, Gilbody, Duley, & Sutton (2000) · Health Technology Assessment · doi:10.3310/hta4100 · Cited by 427 · see citing works
Analyzing incomplete longitudinal clinical trial data
Molenberghs, G. (2004) · Biostatistics · doi:10.1093/biostatistics/kxh001 · Cited by 378 · see citing works
Clinical Trial Registration — Looking Back and Moving Ahead
Laine, C. M., Horton, R. C., DeAngelis, C. D., Drazen, J. M., Frizelle, F., Godlee, F., Haug, C. J., Hébert, P. C., Kotzin, S., Marušić, A., et al. (2007) · New England Journal of Medicine · doi:10.1056/nejme078110 · Cited by 320 · see citing works
Soares, H. P., Daniels, S., Kumar, A., Clarke, M. J., Scott, C., Swann, S., & Djulbegović, B. (2004) · BMJ · doi:10.1136/bmj.328.7430.22 · Cited by 310 · see citing works
Bryant, J., Clegg, A. P., Nicholson, T., McIntyre, L., Broe, S. D., Gerard, K., & Waugh, N. R. (2001) · Health Technology Assessment · doi:10.3310/hta5010 · Cited by 246 · see citing works
Krleža-Jerić, K., Chan, A., Dickersin, K., Sim, I., Grimshaw, J., & Gluud, C. N. (2005) · BMJ · doi:10.1136/bmj.330.7497.956 · Cited by 236 · see citing works
Self-citationDiscordance between reported intention-to-treat and per protocol analyses
Porta, N., Bonet, C., & Cobo, E. (2007) · Journal of Clinical Epidemiology · doi:10.1016/j.jclinepi.2006.09.013 · Cited by 184 · see citing works
Reporting Mortality Findings in Trials of Rofecoxib for Alzheimer Disease or Cognitive Impairment
Psaty, B. M., & Kronmal, R. A. (2008) · JAMA · doi:10.1001/jama.299.15.1813 · Cited by 173 · see citing works
Clinical trial registration: transparency is the watchword
Sim, I., Chan, A.-W., Gülmezoglu, A. M., Evans, T., & Pang, T. (2006) · The Lancet · doi:10.1016/s0140-6736(06)68708-4 · Cited by 165 · see citing works
Self-citationSample size and statistical power of randomised, controlled trials in orthopaedics
Freedman, K. B., Back, S. J., & Bernstein, J. M. (2001) · Journal of Bone and Joint Surgery - British Volume · doi:10.1302/0301-620x.83b3.10582 · Cited by 140 · see citing works
Gravel, J., Opatrny, L., & Shapiro, S. (2007) · Clinical Trials · doi:10.1177/1740774507081223 · Cited by 135 · see citing works
Laine, C. M., Horton, R. C., DeAngelis, C. D., Drazen, J. M., Frizelle, F., Godlee, F., Haug, C. J., Hébert, P. C., Kotzin, S., Marušić, A., et al. (2007) · JAMA · doi:10.1001/jama.298.1.jed70037 · Cited by 135 · see citing works
Reporting of 6-Month vs 12-Month Data in a Clinical Trial of Celecoxib
Hrachovec, J. B., & Mora, M. (2001) · JAMA · doi:10.1001/jama.286.19.2398-c · Cited by 132 · see citing works
Selective reporting in clinical trials: analysis of trial protocols accepted by The Lancet
Al-Marzouki, S., Roberts, I., Evans, S., & Marshall, T. (2008) · The Lancet · doi:10.1016/s0140-6736(08)61060-0 · Cited by 119 · see citing works
Statistical power, sample size, and their reporting in randomized controlled trials
Moher, D. (1994) · JAMA · doi:10.1001/jama.272.2.122 · Cited by 113 · see citing works
Expression of Concern Reaffirmed
Curfman, G. D., Morrissey, S., & Drazen, J. M. (2006) · New England Journal of Medicine · doi:10.1056/nejme068054 · Cited by 109 · see citing works
Underpowering in randomized trials reporting a sample size calculation
Vickers, A. J. (2003) · Journal of Clinical Epidemiology · doi:10.1016/s0895-4356(03)00141-0 · Cited by 102 · see citing works
Hahn, S., Williamson, P. R., & Hutton, J. L. (2002) · Journal of Evaluation in Clinical Practice · doi:10.1046/j.1365-2753.2002.00314.x · Cited by 97 · see citing works
Study of information submitted by drug companies to licensing authorities.
Hemminki, E. (1980) · BMJ · doi:10.1136/bmj.280.6217.833 · Cited by 96 · see citing works
Constraints on Publication Rights in Industry-Initiated Clinical Trials
Gøtzsche, P. C., Hróbjartsson, A., Johansen, H. K., Haahr, M. T., Altman, D. G., & Chan, A.-W. (2006) · JAMA · doi:10.1001/jama.295.14.1645 · Cited by 81 · see citing works
Self-citationWeaver, C. S., Leonardi-Bee, J., Bath-Hextall, F. J., & Bath, P. M. W. (2004) · Stroke · doi:10.1161/01.str.0000125010.70652.93 · Cited by 67 · see citing works
Hernández, A. V., Steyerberg, E., Taylor, G., Marmarou, A., Habbema, J., & Maas, A. (2005) · Neurosurgery · doi:10.1227/01.neu.0000186039.57548.96 · Cited by 62 · see citing works
Community provision of hearing aids and related audiology services.
Reeves, Alborz, Hickson, Bamford, & Gosden (2000) · Health Technology Assessment · doi:10.3310/hta4040 · Cited by 60 · see citing works
Baron, G., Boutron, I., Giraudeau, B., & Ravaud, P. (2005) · Arthritis & Rheumatism · doi:10.1002/art.21116 · Cited by 59 · see citing works
Subgroups, treatment effects, and baseline risks: Some lessons from major cardiovascular trials
Parker, A. B., & Naylor, C. D. (2000) · American Heart Journal · doi:10.1067/mhj.2000.106610 · Cited by 57 · see citing works
A Taxpayer-Funded Clinical Trials Registry and Results Database
Turner, E. H. (2004) · PLoS Medicine · doi:10.1371/journal.pmed.0010060 · Cited by 56 · see citing works
How useful are unpublished data from the Food and Drug Administration in meta-analysis?
MacLean, C. H., Morton, S. C., Ofman, J. J., Röth, E., & Shekelle, P. (2003) · Journal of Clinical Epidemiology · doi:10.1016/s0895-4356(02)00520-6 · Cited by 52 · see citing works
Statistical Considerations in the Intent-to-Treat Principle
Lachin, J. M. (2000) · Controlled Clinical Trials · doi:10.1016/s0197-2456(00)00092-1 · Cited by 51 · see citing works
Waiving confidentiality for the greater good
Chan, A., Upshur, R. E. G., Singh, J. A., Ghersi, D., Chapuis, F. R., & Altman, D. G. (2006) · BMJ · doi:10.1136/bmj.332.7549.1086 · Cited by 46 · see citing works
Self-citationJones, G., & Abbasi, K. A. (2004) · BMJ · doi:10.1136/bmj.329.7479.1360 · Cited by 36 · see citing works
Hebert, R. S., Wright, S. M., Dittus, R. S., & Elasy, T. A. (2002) · Journal of Negative Results in BioMedicine · doi:10.1186/1477-5751-1-1 · Cited by 36 · see citing works
Peer review of statistics in medical research. Rationale for requiring power calculations is needed.
Altman, D. G., Moher, D., & Schulz, K. F. (2002) · PubMed · Cited by 32 · see citing works
Self-citationReporting on methods of subgroup analysis in clinical trials: a survey of four scientific journals
Moreira, E. D., STEIN, Z. A., & Susser, E. (2001) · Brazilian Journal of Medical and Biological Research · doi:10.1590/s0100-879x2001001100011 · Cited by 28 · see citing works
The Challenge of Subgroup Analyses — Reporting without Distorting
(2006) · New England Journal of Medicine · doi:10.1056/nejmx060035 · Cited by 28 · see citing works
An Overview of Statistical Approaches for Adaptive Designs and Design Modifications
Schäfer, H., Timmesfeld, N., & Müller, H. (2006) · Biometrical Journal · doi:10.1002/bimj.200510234 · Cited by 26 · see citing works
Randomized Trials Stopped Early for Benefit: A Systematic Review
Montori, V. M., Devereaux, P. J., Adhikari, N. K. J., Burns, K. E. A., Eggert, C. H., Briel, M., Lacchetti, C., Leung, T. W., Darling, E., Bryant, D. M., et al. (2005) · JAMA · doi:10.1001/jama.294.17.2203 · Cited by 26 · see citing works
Schiffner, R., Schiffner-Rohe, J., Gerstenhauer, M., et al. (2001) · British Journal of Dermatology · doi:10.1046/j.1365-2133.2001.04234.x · Cited by 25 · see citing works
Are trust doctors the new lost tribe?
Cooper, N., & Burr, B. (2002) · BMJ · doi:10.1136/bmj.325.7362.491 · Cited by 22 · see citing works
McNamee, D., James, A., & Kleinert, S. (2008) · The Lancet · doi:10.1016/s0140-6736(08)61053-3 · Cited by 19 · see citing works
Darling, H. (2003) · PubMed · Cited by 10 · see citing works
Flagged first, then by citations
Research works printed but not linked: 4
- [6]Murray GD. Research governance must focus on research training. BMJ 2001; 322: 1461-2.
- [30]PLoS Med. Guidelines for authors. http://journals.plos.org/plosmedicine/guidelines.php#supporting.
- [31]Altman DG, Moher D, Schulz KF. Peer review of statistics in medical research: reporting power calculations is important. BMJ 2002; 325: 491. 12211233
- [46]Chan AW, Tetzlaff J, Altman DG, Gøtzsche PC, Hróbjartsson A, Krleža-Jeric K, et al. The SPIRIT initiative: defining standard protocol items for randomised trials. German J Evid Quality Health Care (suppl) 2008; 102: S27.
Cited by
Sorted by citations
Moher, D., Hopewell, S., Schulz, K. F., Montori, V., Gotzsche, P. C., Devereaux, P. J., Elbourne, D., Egger, M., & Altman, D. G. (2010) · BMJ · doi:10.1136/bmj.c869 · Cited by 8,883 · see citing works
Self-citationSPIRIT 2013 Statement: Defining Standard Protocol Items for Clinical Trials
Chan, A.-W., Tetzlaff, J. M., Altman, D. G., Laupacis, A., Gøtzsche, P. C., Krleža-Jerić, K., Hróbjartsson, A., Mann, H., Dickersin, K., Berlin, J. A., et al. (2013) · Annals of Internal Medicine · doi:10.7326/0003-4819-158-3-201302050-00583 · Cited by 7,363 · see citing works
Self-citationSPIRIT 2013 explanation and elaboration: guidance for protocols of clinical trials
Chan, A.-W., Tetzlaff, J. M., Gotzsche, P. C., Altman, D. G., Mann, H., Berlin, J. A., Dickersin, K., Hrobjartsson, A., Schulz, K. F., Parulekar, W. R., et al. (2013) · BMJ · doi:10.1136/bmj.e7586 · Cited by 6,251 · see citing works
Self-citationMoher, D., Hopewell, S., Schulz, K. F., Montori, V., Gøtzsche, P. C., Devereaux, P. J., Elbourne, D., Egger, M., & Altman, D. G. (2012) · International Journal of Surgery · doi:10.1016/j.ijsu.2011.10.001 · Cited by 2,345 · see citing works
Self-citationMoher, D., Hopewell, S., Schulz, K. F., Montori, V., Gøtzsche, P. C., Devereaux, P. J., Elbourne, D., Egger, M., & Altman, D. G. (2010) · Journal of Clinical Epidemiology · doi:10.1016/j.jclinepi.2010.03.004 · Cited by 1,858 · see citing works
Self-citationSuñé, P., Suñé, J. M., & Montoro, J. B. (2013) · PLoS ONE · doi:10.1371/journal.pone.0054583 · Cited by 1,687 · see citing works
Hopewell, S., Dutton, S., Yu, L.-M., Chan, A.-W., & Altman, D. G. (2010) · BMJ · doi:10.1136/bmj.c723 · Cited by 504 · see citing works
Self-citationOutcome Reporting Among Drug Trials Registered in ClinicalTrials.gov
Bourgeois, F. T., Murthy, S., & Mandl, K. D. (2010) · Annals of Internal Medicine · doi:10.7326/0003-4819-153-3-201008030-00006 · Cited by 332 · see citing works
Mining Electronic Health Records (EHRs): A Survey
Yadav, P., Steinbach, M., Kumar, V., & Simon, G. (2018) · ACM Computing Surveys · doi:10.1145/3127881 · Cited by 299 · see citing works
Page, M. J., McKenzie, J. E., Kirkham, J., Dwan, K., Kramer, S., Green, S., & Forbes, A. (2014) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.mr000035.pub2 · Cited by 281 · see citing works
Reporting of sample size calculation in randomised controlled trials: review
Charles, P., Giraudeau, B., Dechartres, A., Baron, G., & Ravaud, P. (2009) · BMJ · doi:10.1136/bmj.b1732 · Cited by 274 · see citing works
Comparison of protocols and registry entries to published reports for randomised controlled trials
Dwan, K., Altman, D. G., Cresswell, L., Blundell, M., Gamble, C. L., & Williamson, P. R. (2011) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.mr000031.pub2 · Cited by 243 · see citing works
Self-citationDwan, K., Altman, D. G., Clarke, M., Gamble, C., Higgins, J. P. T., Sterne, J. A. C., Williamson, P. R., & Kirkham, J. J. (2014) · PLoS Medicine · doi:10.1371/journal.pmed.1001666 · Cited by 187 · see citing works
Self-citationSPIRIT 2025 explanation and elaboration: updated guideline for protocols of randomised trials
Hróbjartsson, A., Boutron, I., Hopewell, S., Moher, D., Schulz, K. F., Collins, G. S., Tunn, R., Aggarwal, R., Berkwits, M., Berlin, J. A., et al. (2025) · BMJ · doi:10.1136/bmj-2024-081660 · Cited by 171 · see citing works
Self-citationBias, Spin, and Misreporting: Time for Full Access to Trial Protocols and Results
Chan, A.-W. (2008) · PLoS Medicine · doi:10.1371/journal.pmed.0050230 · Cited by 144 · see citing works
Self-citationMayo-Wilson, E., Fusco, N., Li, T., Hong, H., Canner, J. K., & Dickersin, K. (2017) · Journal of Clinical Epidemiology · doi:10.1016/j.jclinepi.2017.05.007 · Cited by 131 · see citing works
Ensuring the quality and specificity of preregistrations
Bakker, M., Veldkamp, C. L. S., van Assen, M. A. L. M., Crompvoets, E. A. V., Ong, H. H., Nosek, B. A., Soderberg, C. K., Mellor, D., & Wicherts, J. M. (2020) · PLOS Biology · doi:10.1371/journal.pbio.3000937 · Cited by 138 · see citing works
Systematic Evaluation of the Patient-Reported Outcome (PRO) Content of Clinical Trial Protocols
Kyte, D., Duffy, H., Fletcher, B., Gheorghe, A., Mercieca-Bebber, R., King, M., Draper, H., Ives, J., Brundage, M., Blazeby, J., et al. (2014) · PLoS ONE · doi:10.1371/journal.pone.0110229 · Cited by 82 · see citing works
Review and publication of protocol submissions to Trials – what have we learned in 10 years?
Li, T., Boutron, I., Salman, R. A.-S., Cobo, E., Flemyng, E., Grimshaw, J. M., & Altman, D. G. (2017) · Trials · doi:10.1186/s13063-016-1743-0 · Cited by 66 · see citing works
Self-citationClark, T., Berger, U., & Mansmann, U. (2013) · BMJ · doi:10.1136/bmj.f1135 · Cited by 68 · see citing works
Out of sight but not out of mind: how to search for unpublished clinical trial evidence
Chan, A.-W. (2012) · BMJ · doi:10.1136/bmj.d8013 · Cited by 62 · see citing works
Self-citationNorris, S. L., Moher, D., Reeves, B. C., Shea, B., Loke, Y., Garner, S., Anderson, L., Tugwell, P., & Wells, G. (2013) · Research Synthesis Methods · doi:10.1002/jrsm.1062 · Cited by 50 · see citing works
Blumle, A., Meerpohl, J. J., Rucker, G., Antes, G., Schumacher, M., & von Elm, E. (2011) · BMJ · doi:10.1136/bmj.d1828 · Cited by 44 · see citing works
Tan, Z. W., Tan, A. C., Li, T., Harris, I., Naylor, J. M., Siebelt, M., van Tiel, J., Pinheiro, M., Harris, L., Chamberlain, K., et al. (2020) · BMJ Open · doi:10.1136/bmjopen-2020-038283 · Cited by 37 · see citing works
TARG Meta-Research Group & Collaborators (2023) · BMJ Open · doi:10.1136/bmjopen-2023-076264 · Cited by 33 · see citing works
Fan, J., Song, F., & Bachmann, M. O. (2019) · Journal of Clinical Epidemiology · doi:10.1016/j.jclinepi.2018.12.009 · Cited by 31 · see citing works
Stegert, M., Kasenda, B., von Elm, E., You, J. J., Blümle, A., Tomonaga, Y., Saccilotto, R., Amstutz, A., Bengough, T., Briel, M., et al. (2016) · Journal of Clinical Epidemiology · doi:10.1016/j.jclinepi.2015.05.023 · Cited by 30 · see citing works
Liu, X., Zhang, X., Wen, S., Peng, L., Hong, Q., & Kang, D. (2015) · Journal of Evidence-Based Medicine · doi:10.1111/jebm.12173 · Cited by 22 · see citing works
Speich, B., Odutayo, A., Peckham, N., Ooms, A., Stokes, J. R., Saccilotto, R., Gryaznov, D., von Niederhäusern, B., Copsey, B., Altman, D. G., et al. (2022) · Trials · doi:10.1186/s13063-022-06516-1 · Cited by 21 · see citing works
Self-citationNejstgaard, C. H., Boutron, I., Chan, A.-W., Chow, R., Hopewell, S., Masalkhi, M., Moher, D., Schulz, K. F., Shlobin, N. A., Østengaard, L., et al. (2023) · Journal of Clinical Epidemiology · doi:10.1016/j.jclinepi.2023.01.003 · Cited by 21 · see citing works
Self-citationSelective outcome reporting: telling and detecting true lies. The state of the science
Macura, A., Abraha, I., Kirkham, J., Gensini, G. F., Moja, L., & Iorio, A. (2010) · Internal and Emergency Medicine · doi:10.1007/s11739-010-0371-z · Cited by 19 · see citing works
Schönenberger, C. M., Griessbach, A., Taji Heravi, A., Gryaznov, D., Gloy, V. L., Lohner, S., Klatte, K., Ghosh, N., Lee, H., Mansouri, A., et al. (2022) · Journal of Clinical Epidemiology · doi:10.1016/j.jclinepi.2022.05.014 · Cited by 17 · see citing works
Access to unpublished protocols and statistical analysis plans of randomised trials
Campbell, D., McDonald, C., Cro, S., Jairath, V., & Kahan, B. C. (2022) · Trials · doi:10.1186/s13063-022-06641-x · Cited by 13 · see citing works
- Authors
- Chan, A.-W., Hrobjartsson, A., Jorgensen, K. J., Gotzsche, P. C., & Altman, D. G.
- Affiliations
- Mayo Clinic (US)
- Cochrane (DK)
- University of Oxford (GB)
- Corresponding author
- Chan, A.-W.
- ORCID
- Altman, D. G
- Venue
- BMJ
- Publisher
- BMJ
- Published
- 2008-12-04
- Volume
- 337
- Issue
- dec04 1
- Pages
- a2299-a2299
- ISSN
- 0007-1447 (ISSN-L)
- 0959-8138
- 1468-5833
- PMC
- PMC2600604
- OpenAlex
- W2074736802
- Cited by
- 202
- References
- 59
- Citations by year
- 2026: 4 · 2025: 4 · 2024: 9 · 2023: 9 · 2022: 10 · 2021: 15 · 2020: 16 · 2019: 6 · 2018: 15 · 2017: 11 · 2016: 10 · 2015: 9 · 2014: 14 · 2013: 9 · 2012: 16
- FWCI
- 17.02
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- cc-by-nc
- Locations
- BMJ (publishedVersion, cc-by-nc)
- Europe PMC (PubMed Central) (publishedVersion, cc-by-nc)
- PubMed Central (publishedVersion, cc-by-nc)
- PubMed (publishedVersion)
- Research at the University of Copenhagen (University of Copenhagen) (publishedVersion)
- University of Southern Denmark Research Portal (University of Southern Denmark) (publishedVersion, cc-by)
- Topics
- Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
- Life Sciences › Pharmacology, Toxicology and Pharmaceutics › Pharmacology › Pharmaceutical industry and healthcare
- Keywords
- sample size determination, statistical methods reporting, randomized controlled trials, missing data handling, protocol deviations, subgroup analysis, interim analysis
- MeSH terms
- Data Collection, Data Interpretation, Statistical, Publishing, Retrospective Studies, Cohort Studies, Randomized Controlled Trials as Topic, Sample Size
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
Are you an author, or do you see a problem with this page? Request a review
