Food

Food questions are the best estimation practice available, because you can check almost every answer against your own week. How much coffee, cheese, bread or sugar a person consumes is something you can reason about directly, and national totals are that per-person figure multiplied by a population you know.

The systematic error is hidden consumption. Most of the sugar, cheese, eggs and oil a person eats arrives inside prepared food rather than as a visible ingredient, so estimating from meals you can picture always undershoots. Per-capita figures include everything, including what you never noticed eating.

Two caveats recur throughout. Availability is not consumption — many national figures measure what entered the food system rather than what was eaten, and the gap is waste. And industry-body figures, which several questions here rely on, are credible in magnitude and promotional in precision. Both are flagged where they apply.