11. Further Topics

  1. Bee Choo Tai1 and
  2. David Machin2

Published Online: 11 OCT 2013

DOI: 10.1002/9781118721957.ch11

Regression Methods for Medical Research

Regression Methods for Medical Research

How to Cite

Tai, B. C. and Machin, D. (2013) Further Topics, in Regression Methods for Medical Research, John Wiley & Sons Ltd, Oxford. doi: 10.1002/9781118721957.ch11

Author Information

  1. 1

    Saw Swee Hock School of Public Health, National University of Singapore and National University Health System; Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore

  2. 2

    Medical Statistics Unit, School of Health and Related Sciences, University of Sheffield; Cancer Studies, Faculty of Medicine, University of Leicester, Leicester, UK

Publication History

  1. Published Online: 11 OCT 2013
  2. Published Print: 29 NOV 2013

ISBN Information

Print ISBN: 9781444331448

Online ISBN: 9781118721957



  • fractional polynomials;
  • model structure;
  • multi-level


This chapter describes some applications of fractional polynomials, which allow more flexible regression models to be considered. It considers circumstances in which y, the endpoint variable, itself is also assessed before randomization. In certain situations, the method of delivery of the intervention prevents it being given on an individual participant basis, rather it can only be delivered to collections of individuals. In the designs the associated auto-correlation implies that the next recorded observation from an individual can be predicted to some extent by previous values. Although we have used a continuous measure as the endpoint in our illustration of multi-level modeling, the methods can be adapted to settings with binary, ordered categorical, count or survival time endpoints.