MIDDLE & SPREAD / AN INVENTED-DATA DEMONSTRATION

Same middle.
Different stories.

A median hides the rest of a distribution. Switch between three sets of nine invented, complete lifetimes and watch what stays the same. These are arithmetic examples, not estimates for dogs or breeds.

One middle, different spread

Median
Arithmetic mean
Observed range

All nine invented records, in ascending order
Record	Invented lifetime in years

JavaScript is off. First invented dataset: 6, 8, 10, 11, 12, 13, 14, 16, 18 years. The mean and median are 12 years; the observed range is 6 to 18 years. The interactive comparison needs JavaScript.

What the diagram does not show

All nine invented lifetimes are complete. Real longevity research may include animals still alive when information ends. A survival analysis accounts for that incomplete follow-up; this simple sorted list does not. The endpoints shown are invented observations, not limits for real dogs.

McMillan et al.: Longevity of companion dog breeds ↗Evidence for this context, not a review or endorsement of Longview.

A reason to read the method

The 2024 paper estimates median survival. The 2022 paper builds life tables and reports an age-zero mean. Neither is an individual death date. The board is an original arithmetic illustration, not a validated clinical tool or a reproduction of either dataset.

Teng et al.: Life tables for UK companion dogs ↗Evidence for this context, not a review or endorsement of Longview.

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