Understanding Statistics

Patient Information

It’s all about reading and interpreting statistics

Risk increased by 500%! Sounds dramatic, doesn’t it? But is it in every case? A risk describes the possibility of an unwanted event. It does not say that you will experience this. Figures can be misleading. To understand figures correctly, the context is important. And not every dramatic headline on medicines is fact-based and reliable.

Three examples.

It depends. The sentence relates the risks of two groups of people. It does not say how many men and women are actually affected.

If the sentence applies to three women and two men in a population of two million, the danger will be fairly small. But if it applies to 30 women and 20 men in a group of 100, the risk will indeed be higher.

The sentence says that 20 out of 100 people who use the drug experience the side effect. If you use the medicine, your risk is 1:5. In the world of risk assessment, this is a fairly high figure.

Nonetheless: in the vast majority of patients in this example – 80% – the side effect does not occur.

Stopping your medication on your own accord is never a good idea, however. If you have any concerns, you should talk to your doctor or pharmacist first before making any changes to your treatment.

Positive news can be just as misleading as negative news. This example does not provide any reliable information on the drug, its effects or even the survey itself.

262 people – this number could stand for 90% in a small survey of 300, or less than 6% if 5,000 participated in the survey.

Furthermore, a survey of personal opinions – especially when its methods and authors are unknown – cannot be a reliable source for assessing the benefits and risks of a drug.

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