STRATOS initiative

The validity and practical utility of observational medical research depends critically on good study design, excellent data quality, appropriate statistical methods and accurate interpretation of results. Statistical methodology has seen substantial development in recent times. Unfortunately, many of these methodological developments are ignored in practice. Consequently, design and analysis of observational studies often exhibit serious weaknesses. The lack of guidance on vital practical issues discourages many applied researchers from using more sophisticated and possibly more appropriate methods when analyzing observational studies. Furthermore, many analyses are conducted by researchers with a relatively weak statistical background and limited experience in using statistical methodology and software. Consequently, even ‘standard’ analyses reported in the medical literature are often flawed, casting doubt on their results and conclusions. An efficient way to help researchers to keep up with recent methodological developments is to develop guidance documents that are spread to the research community at large.

These observations led to the initiation of the STRATOS (STRengthening Analytical Thinking for Observational Studies) initiative, a large collaboration of experts in many different areas of biostatistical research. The objective of STRATOS is to provide accessible and accurate guidance in the design and analysis of observational studies. The guidance is intended for applied statisticians and other data analysts with varying levels of statistical education, experience and interests (click to enlarge).

The Steering Group has decided to start with seven topics of general interest. Two topic groups were added later. Guidance documents will be developed by separate topic groups (TGs), each comprising experts in different area of statistical methodology, alongside applied researchers who may represent future end-users of the STRATOS documents. Each TG will start by developing guidance aimed primarily at level 2 statistical knowledge, which is perhaps slightly below state of the art. STRATOS structure and the initial road map (click to enlarge) from Sauerbrei et al 2014. The STRATOS initiative is closely connected to the International Society of Clinical Biostatistics (ISCB) and was launched at a half-day Mini-Symposium on the last day of the ISCB meeting in Munich, in August 2013.

Topic Groups

Missing data
Chairs: James Carpenter, Kate Lee
Selection of variables and functional forms in multivariable analysis
Chairs: Georg Heinze, Aris Perperoglou, Willi Sauerbrei
Initial data analysis
Chairs: Marianne Huebner, Lara Lusa, Carsten Oliver Schmidt
Measurement error and misclassification
Chairs: Victor Kipnis, Pamela Shaw
Study design
Chairs: Suzanne Cadarette, Mitchell Gail
Evaluating diagnostic tests and prediction models
Chairs: Ewout Steyerberg, Ben van Calster
Causal inference
Chairs: Els Goetghebeur, Ingeborg Waernbaum
Survival analysis
Chairs: Michal Abrahamowicz, Malka Gorfine, Terry Therneau
High-dimensional data
Chairs: Riccardo De Bin, Lisa McShane, Joerg Rahnenfuehrer


To co-ordinate the initiative, to share best research practices and to disseminate research tools and results from the work of the topic groups (TG), several cross-cutting panels have been started recently. They aim to develop recommendations (sometimes rather loose as for simulation studies, sometimes more strict as for STRATOS publications) and to provide the infrastructure for those aspects of the initiative that apply to all or most of the TGs, and to coordination of the efforts of the individual TGs. Recommendations aim to support, simplify and harmonize work within and across the TGs. They will also help increase transparency in deriving guidance documents in STRATOS.

The following Panels have been created to date:

Chairs: James Carpenter, Willi Sauerbrei
Chairs: Bianca De Stavola, Mitchell Gail, Pamela Shaw, Mark Baillie (Visualisation)
Chairs: Martin Boeker, Marianne Huebner
Chairs: Joerg Rahnenfuehrer, Willi Sauerbrei
Literature Review
Chairs: Gary Collins, Carl Moons
Chairs: n.n.
Simulation Studies
Chairs: Michal Abrahamowicz, Anne-Laure Boulesteix
Data Sets
Chairs: Saskia Le Cessie, Maarten van Smeden
Knowledge Translation
Chair: Maarten van Smeden
Contact Organizations
Chairs: Willi Sauerbrei
Chair: Mark Baillie
Open science
Chair: Sabine Hoffmann