Home banner
A-Z Index

Quick way to the find the information that you need...

More button
Register with FRAME

Although you do not need to register, any information you provide will be confidential and used only by FRAME to improve the website

Register button
Account Login
Forgot password?

The Journal


Alternatives to Laboratory Animals - ATLA

Download latest issue button Download back issues button Subscribe to ATLA
Contact Us

Tel icon

Tel: +44 (0)115 9584740

Tel icon

Fax: +44 (0)115 9503570

Make an Enquiry

Interpretation of two-stage experiments in animal studies.

Horgan, G. W.

Laboratory Animals, 39(1), 75-79 (2005)

Two-stage experiments allow results to be analysed at the end of the first stage and the second stage to be omitted if the preliminary conclusions are clear-cut. They thus offer the potential to reduce the number of experimental animals. However, using standard P values to assess the significance of results at the end of either stage will lead to an increase in risk of false positive conclusions. This paper provides a possible protocol for two-stage experiments and a method for adjusting P values. It is shown that, for experiments with reasonable power (>80%), the expected reduction in animal numbers will be at least 20%.