The Explanatory Essays in The James Lind Library were written to promote wider understanding of why fair tests of treatments are needed, and what they have come to consist of [Chalmers 2008, Clarke 2022] .

The Informed Health Choices (IHC) Essays complement the Explanatory Essays by focusing on the use of information from fair tests of treatments to inform decisions.

The James Lind Library’s Book of Explanatory Essays

The explanatory essays in The James Lind Library have been rewritten in book format, with illustrations and examples from the history of fair tests.

You can access each individual essay from the menu below.

The text in these essays may be copied and used for non-commercial purposes on condition that explicit acknowledgement is made to The James Lind Library (

These Essays are also available in:  FrançaisPortuguêsРусский, Español,  العربية , 简体中文

Fair tests of treatments

1.0 Introduction to JLL Explanatory Essays

1.1 Why treatment uncertainties should be addressed

1.2 Why treatment comparisons are essential

1.3 Why treatment comparisons must be fair


2.0 Avoiding biased treatment comparisons

2.1 Why comparisons must address genuine uncertainties

2.2 The need to compare like-with-like in treatment comparisons

2.3 Why avoiding differences between treatments allocated and treatments received is important

2.4 The need to avoid differences in the way treatment outcomes are assessed

2.5 Bias introduced after looking at study results

2.6 Reducing biases in judging unanticipated possible treatment effects

2.7 Dealing with biased reporting of the available evidence

2.8 Avoiding biased selection from the available evidence

2.9 Recognizing researcher/sponsor biases and fraud

The play of chance

3.0 Taking account of the play of chance

3.1 Recording and interpreting numbers in testing treatments

3.2 Quantifying uncertainty in treatment comparisons

3.3 Reducing the play of chance using meta-analysis

Bringing it all together for the benefit of patients and the public

4.0 Bringing it all together for the benefit of patients and the public

4.1 Improving reports of research

4.2 Preparing and maintaining systematic reviews of all the relevant evidence

4.3 Using the results of research