Medical Writing Observational Studies Guidance for the design and analysis of observational studies: The STRengthening Analytical Thinking for Observational Studies (STRATOS) initiative

Volume 26, Issue 3 - Observational Studies

Guidance for the design and analysis of observational studies: The STRengthening Analytical Thinking for Observational Studies (STRATOS) initiative


Observational studies pose a number of biostatistical challenges. Methodological approaches have grown exponentially, but most are rarely applied in the real world. The STRengthening Analytical Thinking for Observational Studies (STRATOS) initiative is an international collaboration that was formed to provide guidance to help bridge the gap between methodological innovation and application. STRATOS is focused on identifying issues and promising approaches for planning and analysing observational studies. Crucially, STRATOS will communicate its findings to a wide audience with different levels of statistical knowledge. In this article, we provide an example illustrating the need for such guidance and describe the structure, general approach, and general outlook of the STRATOS initiative.
Download the full article


  1. Altman DG, Lausen B, Sauerbrei W, Schumacher M. Dangers of using “Optimal” cutpoints in the evaluation of prognostic factors. J Natl Cancer Inst 1994;86:829–35. Available from: http://
  2. Ioannidis JP. Why most published research findings are false. PloS Med 2005;2:E124. Available from: http://
  3. The Lancet. Research: increasing value, reducing waste [series]. 2014. Available from: Available from: http://
  4. Kleinert S, Horton R. How should medical science change? Lancet 2014; 383:197–198. Available from: http://
  5. Chalmers I, Glasziou P. Avoidable waste in the production and reporting of research evidence. Lancet 2009;374:86–9. Available from: http://
  6. Ioannidis JP, Greenland S, Hlatky MA, Khoury MJ, Macleod MR, Moher D et al. Increasing value and reducing waste in research design, conduct, and analysis. Lancet 2014;383: 166–175. Available from: http://
  7. Sauerbrei W. Prognostic factors – confusion caused by bad quality of design, analysis and reporting of many studies. In Bier H , editor. Current research in head and neck cancer. Advances in oto-rhinolaryngology. Basel, Karger 2005;62:184–200. Available from: http://
  8. Trouble at the lab. The Economist 2013 Oct 18. Available from: http://
  9. Vickers A. Interpreting data from randomized trials: the Scandinavian prostatectomy study illustrates two common errors. Nat Clin Pract Urol 2005;2:404–5. Available from: http://
  10. Sauerbrei W, Abrahamowicz M, Altman DG, le Cessie S and Carpenter J on behalf of the STRATOS initiative. STRengthening Analytical Thinking for Observational Studies: the STRATOS initiative. Stat Med 2014;33:5413–32. Available from: http://
  11. Royston P, Altman DG, Sauerbrei W. Dichotomizing continuous predictors in multiple regression: a bad idea. Stat Med 2006;25:127–41. Available from: http://
  12. Van Walraven C, Hart RG. Leave ’em alone – why continuous variables should be analyzed as such. Neuroepidemiology 2008;30:138–9. Available from: http://
  13. Sauerbrei W, Royston P. Continuous Variables: To categorize or to model? In: Reading C, editor. The 8th International Conference on Teaching Statistics – Data and Context in statistics education: Towards an evidence based society. International Statistical Institute, Voorburg. 2010. Available from: http://
  14. Royston P, Sauerbrei W. Multivariable model-building – a pragmatic approach to regression analysis based on fractional polynomials for modelling continuous variables. Wiley, Chichester 2008. Available from: http://
  15. Malats N, Bustos A, Nascimento CM, Fernandez F, Rivas M, Puente D et al. P53 as a prognostic marker for bladder cancer: a meta-analysis and review. Lancet Oncol 2005;6:678–86. Available from: http://
  16. Valveny N, Gilliver S. How to interpret and report the results from multivariable analyses. Med Writ 2016;25:37–42. Available from: http://
  17. Lang TA, Altman DG. Statistical analyses and methods in the published literature: The SAMPL guidelines. Med Writ 2016; 25:31–5. Available from: http://
  18. Simera I, Moher D, Hirst A, Hoey J, Schulz KF, Altman DG. Transparent and accurate reporting increases reliability, utility, and impact of your research: reporting guidelines and the EQUATOR Network. BMC Med 2010;8:24. Available from: http://
  19. von Elm E, Altman DG, Egger M, Pocock SJ, Gøtzsche PC, Vandenbroucke JP for the STROBE initiative. The strengthening the reporting of observational studies in epidemiology (STROBE) statement: guidelines for reporting observational studies. Epidemiology 2007;18:800–4. Available from: http://
  20. Cadarette SM, Ban JK, Consiglio GP et al. Diffusion of innovations model helps interpret the comparative uptake of two methodological innovations: co-authorship network analysis and recommendations for the integration of novel methods in practice. J Clin Epidemiol 2017; 84:150–60. Available from: http://



Observations and Observational Studies
President's Message
RCTs: Can the treatment work? Patient registries: Does the treatment work?
Odd cases and risky cohorts: Measures of risk and association in observational studies
Guidance for the design and analysis of observational studies: The STRengthening Analytical Thinking for Observational Studies (STRATOS) initiative
Guidelines for disclosing the results from observational trials
Registration and ethics committee approval for observational studies: Current status and way forward
Regulatory submissions of non-interventional post-authorisation safety studies
Reporting non-interventional post-authorisation safety studies (NI-PASS)
Patient-reported outcomes: How useful are they?
EMA releases the revised Good Pharmacovigilance Practices Module V – updated guidance on risk management plans
Mentoring tomorrow’s medical writers
ICMJE to mandate data sharing statements
News from the EMA
Journal Watch
Getting Your Foot in the Door
In the Bookstores
Regulatory Matters
Medical Communications
The Webscout
Teaching Medical Writing
Good Writing Practice
Out on Our Own

Member Login


The Write Stuff Archive Contact Instructions for Authors Feature Article Template (Word) Journal Policies

Editoral Board



Managing Editor

  • Victoria White (Tampa, Florida, USA) Email:
show all +

Associate Editors:

Section Editors:

Ad-hoc Editors:

  • Amy Whereat (SpeaktheSpeech Consulting, Asnieres sur Seine, France)

Editor Emeritus: