Dependent observations in clinical research

European Journal of Endocrinology, vol. 190, pp. E1–E3

Abstract

For many statistical methods that are commonly used in medical research, it is assumed that observations are independent. However, when this assumption is violated, alternative methods may be needed. In this paper, we describe why an analysis that ignores the dependencies within the data may provide biased results and outline possible alternatives. This paper aims to create awareness among researchers, readers, and reviewers for this possible source of bias in medical research.

Authors 2

1. Rolf H. H. Groenwold corresponding 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 ,

   Department of Clinical Epidemiology, Leiden University Medical Center , Leiden ,

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

   Department of Clinical Epidemiology, Leiden University Medical Center , Leiden , the Netherlands

2. Olaf M. Dekkers Aachen Department of Clinical Epidemiology Department of Endocrinology, Leiden University Medical Center

   Aarhus University · Leiden University Medical Center · Aarhus University Hospital

   Affiliation as printed

   Department of Clinical Epidemiology, Aarhus University and Aarhus University Hospital , Aarhus ,

   Department of Clinical Epidemiology, Leiden University Medical Center , Leiden ,

   Department of Endocrinology, Leiden University Medical Center , Leiden ,

   Department of Clinical Epidemiology, Aarhus University and Aarhus University Hospital , Aarhus , Denmark

   Department of Clinical Epidemiology, Leiden University Medical Center , Leiden , the Netherlands

   Department of Endocrinology, Leiden University Medical Center , Leiden , the Netherlands