4. Design and Sample Size Issues: How Many Subjects Do I Need for My Study?

  1. Stephen J. Walters

Published Online: 10 SEP 2009

DOI: 10.1002/9780470840481.ch4

Quality of Life Outcomes in Clinical Trials and Health-Care Evaluation: A Practical Guide to Analysis and Interpretation

Quality of Life Outcomes in Clinical Trials and Health-Care Evaluation: A Practical Guide to Analysis and Interpretation

How to Cite

Walters, S. J. (2009) Design and Sample Size Issues: How Many Subjects Do I Need for My Study?, in Quality of Life Outcomes in Clinical Trials and Health-Care Evaluation: A Practical Guide to Analysis and Interpretation, John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/9780470840481.ch4

Author Information

  1. School of Health and Related Research, University of Sheffield, UK

Publication History

  1. Published Online: 10 SEP 2009
  2. Published Print: 25 SEP 2009

ISBN Information

Print ISBN: 9780470753828

Online ISBN: 9780470686140

SEARCH

Keywords:

  • method of statistical analysis and QoL data collected;
  • sample size calculations for research protocols;
  • significance tests, P-values and power;
  • design and sample size issues;
  • two independent group comparison;
  • Community Postnatal Support Worker (CPSW) study;
  • Natural logarithm of SF-36 Physical Functioning dimension;
  • QoL outcomes condensed into binary or dichotomous categorical scale;
  • sample size method with quality of life outcomes;
  • standard deviation of QoL outcome

Summary

This chapter contains sections titled:

  • Summary

  • Introduction

  • Significance tests, P-values and power

  • Sample sizes for comparison of two independent groups

  • Choice of sample size method with quality of life outcomes

  • Paired data

  • Equivalence/non-inferiority studies

  • Unknown standard deviation and effect size

  • Cluster randomized controlled trials

  • Non-response

  • Unequal groups

  • Multiple outcomes/endpoints

  • Three or more groups

  • What if we are doing a survey, not a clinical trial?

  • Sample sizes for reliability and method comparison studies

  • Post-hoc sample size calculations

  • Conclusion: Usefulness of sample size calculations

  • Further reading