Method

Primary means first-hand. A source is primary when it holds the data itself, not when it is respectable. The Bank of Japan is primary on the money supply. A broker is primary on its own transactions. A newspaper reporting either one is not primary on anything — it is a pointer to where the number lives.

The hierarchy has three levels and the third is a prohibition. An official consolidated source is the ideal: the FSA, the GIAJ, the LIAJ, the BOJ. Where no official consolidation exists, we use an attributed non-official source and say so plainly — a figure that has no official seal is not the same as a figure with no origin, and flattening the two would mean publishing less than we honestly can. What we do not do is take a number from a source that is citing someone else, or from a figure whose trail runs out. If we cannot follow it back to the body that produced it, it does not go up.

Verification means the original document, not the total. A figure is checked against the release it came from, line by line. Reconciling to a published total is not the same thing — an aggregate can balance with compensating errors inside it, and we have found exactly that in our own working files. Units get checked separately, because Japanese sources move between 百万円, 十億円 and 兆円 across tables in the same document, and a mislabelled unit is a factor-of-a-thousand error that no total will catch.

When sources disagree or revise, we say so. Official figures get revised; two bodies measuring similar things with different methods produce different numbers, and neither is wrong. Where that happens, we publish the discrepancy rather than picking a winner quietly, and we name the methodology that separates them. A revision is dated, not overwritten.

What travels with every figure: its origin, its date, and its revision state. Enough to take any number here, go to the body that issued it, and find the same number. That is the standard. Where a figure cannot meet it, it does not appear — and where a whole measure cannot be built from primary sources, we say that too, instead of estimating our way around the gap.

Credit where credit’s due: This project would not have been possible without my AI assistant.

Two kinds of source, kept separate on purpose

Official primary means the body that produced the number publishes it: a regulator, a ministry, an association, a company reporting on itself. Attributed primary means someone else collected it, and says where each figure came from and how it was compiled.

The second kind is admitted only when the first does not exist, and it is labelled where it appears. The distinction is not about quality. It is about how far you have to go to check a number — one step, or two.

There is a third category we read and do not list: catalogues, archives, and press databases that tell us a figure exists. We go to the issuing body for the number itself. Listing them here would suggest they are sources of data, and they are not.

By domain, not by importance. Nothing here is ranked — a domain has as many entries as the current work needs, and that is all the order means.

A domain appears on this list when something in it is actually being read line by line. Until then it stays off, however obviously it belongs.

The list grows as the platform does. It is a record of what we actually read, not a statement of ambition, and a source appears here once it has been used.