Although a person got better after using a treatment, the treatment may not have helped. It’s possible they would have gotten better without the treatment. It also does not mean that giving another person the same treatment will make them better.
One reason that personal experiences – including a series of personal experiences – are sometimes misleading is that experiences, such as pain, fluctuate and tend to return to a more normal or average level. This is sometimes referred to as “regression to the mean”. For example, people often treat symptoms such as pain when they are very bad and would improve anyway without treatment. The same applies to a series of experiences. For example, if there is a spike in the number of traffic crashes someplace, traffic lights may be installed to reduce these. A subsequent reduction may give the appearance that the traffic lights caused this change. However, it is possible that the number of crashes would have returned to a more normal level without the traffic lights.
BEWARE when someone says: “It worked for me.”