Counting the Uncounted
Before the 19th century, states counted populations for taxing and conscripting. Every pre-modern number was produced by a process the counted had reasons to defeat. Ask what the count was for, and the direction of the bias follows.
| Source | Made for | Systematic distortion |
|---|---|---|
| Tax rolls | Extraction | Under-count: people hide |
| Muster rolls | Conscription | Under-count: sons vanish |
| Parish registers | Religion | Miss unbaptized & mobile |
| Bills of mortality | Plague policy | Guesswork causes of death |
Family reconstitution links parish baptisms, marriages, and burials person by person. This uncovers age at first marriage, birth intervals, and infant mortality. In north-west Europe, women married late (24–26). Since marital fertility was uncontrolled, the age of marriage was the population's brake.
The Multiplier Problem
If you have 400 hearths in 1377 and use a household size multiplier of 4.0 to 5.5, your population swings from 1,600 to 2,200—a 38% range before accounting for evasion.
The honest practice: report assumptions with the number. Give a range rather than a point. A spurious decimal place is not precision; it is a claim about evidence you do not have.
North-west Europe's control loop was unobserved at the time: couples waited for a viable household before marrying. Population responded to the economy through the wedding, discovered centuries later by re-linking records kept for souls.