Understanding childhood, including the one you accompany

A figure like zero point four circulates widely in educational syntheses. Knowing what it measures prevents comparing it to what it does not.

The French scheme was born inside private firms before being generalised by law. That origin explains part of its present shape, including what is still argued about.

Time use surveys have existed since the 1960s and produce a counter-intuitive result: reported parental time has risen, in almost every rich country.

A simple test, in use since 1983, seemed to place around age four the ability to attribute a mistaken belief to someone else. Non-verbal versions have blurred that timetable.

Heritability is one of the most misunderstood words in statistics. It does not describe an individual, and its value changes with the population in which it is computed.

Sweden legislated in 1979, France in 2019. More than sixty states have followed, and evaluating these laws poses particular methodological difficulties.

It is one of the rare family practices tested by controlled trials. Effects exist, and they are better established on vocabulary than on anything else.

A laboratory procedure devised in 1969 still supplies most of the data on attachment. It measures something real, and far narrower than is often claimed.

Most data on young children come from questionnaires completed by an adult. That source has well identified properties, rarely recalled when the results circulate.

Comparing leave duration across countries produces rankings that circulate widely. They conflate entitlements whose pay, transferability and take-up have nothing in common.

A typology formulated in the 1960s still structures the textbooks. It was built on a narrow sample, and its reach beyond that context has been contested ever since.

A child who says nothing may understand a great deal. The gap between what is understood and what is produced is one of the best established facts about language development.

Following the same thousands of children for twenty years is expensive and takes twenty years. It is nonetheless the only design that separates what comes before from what comes after.

In France the obligation starts at three, and has done since 2019. Elsewhere in Europe it starts at four, five, six or seven, and those gaps do not mean what one assumes.

Few subjects set such sharply drawn camps against each other on such thin data. Here is what the published trials actually measure, and what they stay silent on.