The Critical thinking and Appraisal Resource Library (CARL) is a platform to collect and distribute freely-available learning resources intended to help people think critically about treatment claims. Our definition of ‘treatments’ includes any action intended to improve health or relieve suffering. These include changes in behaviour; screening programmes; drugs, surgery, physical and psychological treatments; and public health and healthcare system changes.

CARL is built around the Key Concepts, developed by the Informed Health Choices project, which people need to understand in order to be able to evaluate treatment claims. Populating the CARL database with learning resources has used candidate items from several sources, including pre-existing compilations and relevant systematic reviews. These include:

• Interactive teaching resources compiled in preparation for a multidisciplinary meeting in Oxford in 2011 [Krause 2011]

• Resources compiled as part of the European Communication on Research Awareness Needs (ECRAN) project [Mosconi 2016]

• Resources identified by the Informed Health Choices project

• Resources in Testing Treatments [Evans 2011] and Testing Treatments interactive

• Resources in the James Lind Library

• Resources available through the Educational Endowment Foundation

• Resources available through the Times Education Service

• Resources identified through systematic reviews of teaching/learning interventions [Nordheim 2016; Austvoll-Dahlgren 2016a; Cusack 2016]

• Online searches for additional material


A resource’s relevance to the Key Concepts has been the main determinant of whether a resource would be included. The coding for each resource includes:

• A unique resource identification code.
• The title (as stated by the resource host)
• The format (text, video, audio, lessons (including presentations, e-learning modules and specific materials for teaching students, such as learning exercises or worksheets), cartoons, and websites)
• The URL
• The language
• The Key Concepts to which the resource is relevant
• Target user groups (children and young people, and school teachers); health profession undergraduates; health professionals; journalists, science writers and other communicators; members of the public)
• Evaluations of the resource, with links to reports of the evaluations

Resources that have been formally evaluated are identified and there are links to published accounts of those evaluations. Over 500 resources have been included so far. Only eight of these resources have been formally evaluated.