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

PLoS ONE, vol. 19, pp. e0295726

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 data screening comprises five types of explorations, covering the analysis of participation profiles over time, evaluation of missing data, presentation of univariate and multivariate descriptions, and the depiction of 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-another element 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. Inserm · Bordeaux Population Health

    Affiliation as printed

    Univ. Bordeaux, Inserm, Bordeaux Population Health Research Center, UMR1219, Bordeaux, France

  3. Universitätsmedizin Greifswald · Universität Greifswald

    Affiliation as printed

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

  4. 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. 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. Michigan State University

    Affiliation as printed

    Center for Statistical Training and Consulting, Michigan State University, East Lansing, MI, United States of America

  7. Michigan State University

    Affiliation as printed

    Center for Statistical Training and Consulting, Michigan State University, East Lansing, MI, United States of America

    Department of Statistics and Probability, Michigan State University, East Lansing, MI, United States of America

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References 33