Initial data analysis for longitudinal studies to build a solid foundation for reproducible analysis

medRxiv

Abstract

Abstract Initial data analysis (IDA) is the part of the data pipeline that takes place between the end of data retrieval and the beginning of data analysis that addresses the research question. Systematic IDA and clear reporting of the IDA findings is an important step towards reproducible research. A general framework of IDA for observational studies includes data cleaning, data screening, and possible updates of pre-planned statistical analyses. Longitudinal studies, where participants are observed repeatedly over time, pose additional challenges, as they have special features that should be taken into account in the IDA steps before addressing the research question. We propose a systematic approach in longitudinal studies to examine data properties prior to conducting planned statistical analyses. In this paper we focus on the data screening element of IDA, assuming that the research aims are accompanied by an analysis plan, meta-data are well documented, and data cleaning has already been performed. IDA screening domains are participation profiles over time, missing data, and univariate and multivariate descriptions, and longitudinal aspects. Executing the IDA plan will result in an IDA report to inform data analysts about data properties and possible implications for the analysis plan that are other elements of the IDA framework. Our framework is illustrated focusing on hand grip strength outcome data from a data collection across several waves in a complex survey. We provide reproducible R code on a public repository, presenting a detailed data screening plan for the investigation of the average rate of age-associated decline of grip strength. With our checklist and reproducible R code we provide data analysts a framework to work with longitudinal data in an informed way, enhancing the reproducibility and validity of their work.

Authors 7

1. Lara Lusa corresponding

   University of Primorska · University of Ljubljana

   Affiliation as printed

   Department of Mathematics, Faculty of Mathematics, Natural Sciences and Information Technologies, University of Primorska, Koper/Capodistria, Slovenia

   Institute for Biostatistics and Medical Informatics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia

2. Cécile Proust‐Lima

   Inserm · Bordeaux Population Health

   Affiliation as printed

   Univ. Bordeaux, Inserm, Bordeaux Population Health Research Center, UMR1219, F-33000 Bordeaux, France

   Univ. Bordeaux, Inserm, Bordeaux Population Health Research Center, UMR1219, F-000 Bordeaux, France

3. Carsten Oliver Schmidt

   Universitätsmedizin Greifswald · Universität Greifswald

   Affiliation as printed

   Institute for Community Medicine, SHIP-KEF University Medicine of Greifswald, Greifswald, Germany

4. Katherine J. Lee

   The University of Melbourne · Murdoch Children's Research Institute

   Affiliation as printed

   Clinical Epidemiology and Biostatistics Unit, Murdoch Children’s Research Institute, Melbourne, Australia

   University of Melbourne, Melbourne, Australia

5. Saskia le Cessie Aachen Department of Biomedical Data Sciences Department of Clinical Epidemiology

   Leiden University Medical Center

   Affiliation as printed

   Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, The Netherlands

   Department of Clinical Epidemiology and Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, The Netherlands

6. Frank Lawrence

   Michigan State University

   Affiliation as printed

   Center for Statistical Training and Consulting, Michigan State University, East Lansing, MI, USA

7. Marianne Huebner

   Michigan State University

   Affiliation as printed

   Center for Statistical Training and Consulting, Michigan State University, East Lansing, MI, USA

   Department of Statistics and Probability, Michigan State University, East Lansing, MI, USA,