Part 3: Stories and studies

Chapter 7: An education in shopping

Jenny has been sucked in by the marketing claims for a herbal and vitamin product. She is sure that it’s been a big help for her tennis elbow. But the more she investigates, the more she realises that all might not be as it seems. This case study illustrates many of the common mistakes made by those who rely upon product marketing claims.

Chapter 8: The weakness of one

Anecdotes involving a single person’s experience of an illness or a treatment can be extremely powerful. When you hear one person’s story, it can be more compelling than hearing the results of a randomised controlled trial involving thousands of anonymous people. However, anecdotal evidence is unreliable for many reasons. It is usually unwise to rely on generalisations based on the experiences of only a few people. Randomised controlled trials provide more reliable evidence about the probability that any intervention will cause benefit or harm.

Chapter 9: The power of many

To estimate your chance of recovering from a disease, or of being helped or harmed by an intervention, you need information about the probability of various outcomes. And you need it expressed in a way that you can understand and that is relevant to your needs. If a practitioner tells you that the “risks of this procedure are small”, it is difficult to know what “small” means. It is more helpful, for example, to know that “on average, one in 100 people, or one per cent of people, will experience severe pain after this procedure”. You will be able to make wiser health decisions if you understand the probabilities of benefits and harms occurring with your various options.