In this video, we introduce the median and mean by asking, "Do you have more than the average number of feet?

In this video, we introduce the median and mean by asking, “Do you have more than the average number of feet?”

The example given is a sample of pedestrians, one of whom only has one foot due to cancer surgery. As a result, the

mean is less than the median. We show the process of calculating a median – by lining up the sample from smallest

to tallest – and of a mean – the arithmetic calculations – and emphasize that while someone typically has the median

level of some characteristic (e.g., 2 feet), often no-one has the mean level (e.g., 1.89 feet). This demonstrates the

difference between a calculated parameter (such as a mean) and one that can be directly observed (such as the

median). The video ends by discussing medical risk, arguing that because median risk is generally below mean risk

(often, a small number of individuals are at greatly increased risk), many of us get treatments or tests we don’t need.

Use

This video fits in well in the introductory part of any statistics course because a) it covers basic subjects; b) it takes

something that seems quite trivial, means and medians, and then connects them to a concrete application,

overdiagnosis and overtreatment in the medicine. The video can be accompanied by Chapters 2 and 5 in What is a pvalue

anyway?

In the video, the statistician says that scientific statements have to be very precise and we have to thinkhard about whether they are true. This can lead to discussions about:a. How precise is “very” precise? Should we say e.g., that the mean height of US men is 5’10” orwould it be more “scientific” to say that it is 5’10.23416”?