Standard Article

Baseline Adjustment in Longitudinal Studies

  1. Stephen Senn

Published Online: 15 JUL 2005

DOI: 10.1002/0470011815.b2a12007

Encyclopedia of Biostatistics

Encyclopedia of Biostatistics

How to Cite

Senn, S. 2005. Baseline Adjustment in Longitudinal Studies. Encyclopedia of Biostatistics. 1.

Author Information

  1. University College London, London, UK

Publication History

  1. Published Online: 15 JUL 2005


A baseline variable may be a demographic characteristic such as sex, a pretreatment observation on the variable to be used for measuring outcome, or a pretreatment observation on a variable correlated with the outcome. Adjustment by the analysis of covariance is preferable to the analysis of changes. Topics discussed include testing for baseline balance, adjustment for baselines taken after start of treatment, cut-off designs, cohort studies, and uncontrolled studies.


  • analysis of covariance;
  • change;
  • cut-off;
  • cohort;
  • uncontrolled