Medical Writing Statistics Never P alone: The value of estimates and confidence intervals

Volume 25, Issue 3 - Statistics

Never P alone: The value of estimates and confidence intervals


How results are reported influences how they are interpreted. Although P values have been granted great importance, they have no clinical interpretation. Rather, they are a measure of chance as an explanation for the results. Their either or interpretation takes attention away from the results themselves – the difference between groups or the effect size–which are more important. Effect sizes are also estimates. Estimates are only useful if they are accompanied by a measure of precision. In medicine, this measure is usually the 95% confidence interval (CI). This article explains the concepts underlying CIs and illustrates how they are more useful than P values in reporting research. As such, journals are increasingly asking for CIs, instead of, or at least in addition to, P values.

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  1. Rowntree D. Statistics without tears: an introduction for nonmathematicians. London: Penguin Books; 2000.
  2. Lang TA, Secic M. How to report statistics in medicine: annotated guidelines for authors, editors, and reviewers. 2nd ed. Philadelphia: American College of Physicians; 2006.



Statistics for medical writers
President's Message
History of biostatistics
The illusion of certainty and the certainty of illusion
Never P alone: The value of estimates and confidence intervals
A medical writer's guide to meta-analysis
Study design made easy
Statistical analyses and methods in the published literature: The SAMPL guidelines
How to interpret and report the results from multivariable analyses
Biostatistics and medical writing: Synergy in preparing clinical trials documents
Best friends forever: A pattern of collaboration between medical writers and biostatisticians within the Russian CRO
Where have all the UK entry level pharmaceutical regulatory medical writing jobs gone?
News from the EMA
Journal Watch
In the Bookstores
The Webscout
Good Writing Practice
Medical Communications
Getting Your Foot in the Door
Lingua Franca and Beyond
Gained in Translation
Teaching Medical Writing
Profile: An interview with Professor Peter Jüni on methodology and statistics in scientific manuscripts
Out On Our Own

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