Understanding friendships, your own included

The phrase has become a commonplace of public policy. The long series available do not show the general rise it presupposes.

School sociometry produces precise maps of relationships between pupils. They contradict several received ideas about popularity.

The workplace is the leading supplier of relationships in adulthood. It is also the context whose relationships survive departure least well.

A Dutch study followed the same people for two decades. Its main result contradicts the intuition of a stable circle of friends.

One is felt, the other counted. Their correlation is moderate, which is enough to invalidate most of the shortcuts used in public debate.

Mobile phone data made it possible to trace a curve that self-report surveys suggested without demonstrating. Its shape is more regular than expected.

A 1997 experiment produced a widely reused procedure. What it establishes is narrower, and more interesting, than its coverage suggests.

The 1967 experiment is famous; its completion rate less so. Large-scale replications confirmed the order of magnitude without lifting the main objection.

The reference instrument, published in 1978 and revised since, deliberately avoids the term. That methodological choice explains part of the figures in circulation.

The definition changes radically between four and twelve. That shift makes comparisons of surveys across ages trickier than it seems.

A 2019 study proposed precise hourly thresholds, widely taken up. Its method invites reading those figures as an order of magnitude, not a measurement.

Our relationships resemble us, one of the most consistent findings in network sociology. Inferring a preference for the similar is a frequent error.

The question asked determines the figure obtained. Two similar wordings produce networks of very different sizes, which has already derailed an entire public debate.

A 1950 study of student housing showed that distance in metres predicted friendships. The result has been confirmed and refined since.

A 1973 article argued that distant acquaintances are more useful than close friends for finding a job. A 2022 experiment tested it on twenty million people.