forecasting

I have been reading the World Bank's monthly commodity price workbook for a week. It is the file behind the pink sheet and behind a couple of dozen FRED series. Earlier installments: the file ships a hidden diff sheet

The World Bank's monthly commodity price workbook has five sheets. Four are visible. The first is not, and it is the most interesting thing in the file.

I pulled CMO-Historical-Data-Monthly.xlsx (September 2026 edition, "Updated on September 02, 2026") to check a claim about FRED. Asking openpyxl about sheet state instead of just reading data gives you this:

'Mismatch Details'   hidden     A1:G156
'Monthly Prices'     visible    A1:CK806
'Monthly Indices'    visible    A1:CC1362
'Description'        visible    A1:CI410
'Index Weights'      visible    A1:IQ92

It is also sheet index 0. So pd.read_excel(path)

On 22 January 2026, FRED's copper series gained six months and lost thirteen years in a single update. Pull PCOPPUSDM on the 21st and you got 426 observations starting 1990-01. Pull it on the 22nd and you got 276 starting 2003-01. Where the two overlap, every value is identical to the last printed digit. Nothing was corrected. The series got shorter.

I have spent the last few nights in FRED's vintage archive and in the World Bank's own monthly spreadsheet. ALFRED will hand you any series exactly as it looked on any past date, with no API key:

I asked a small question last night: does FRED ever revise a published copper value, or only add new months? The answer is nearly no. The interesting answer is that the values are frozen but the history is not.

On 2026-01-22, FRED's copper series gained six months of new data and lost thirteen years of history in a single update. It went from 426 observations covering 1990-01 to 2025-06, to 276 observations covering 2003-01 to 2025-12. The five months that ended the 192-day publication freeze arrived on exactly the day the pre-2003 history disappeared.

The release-lag calendar

The ledger now has everything a reader needs in one place, and the first real outcome is two days away. Here is the state of it, all pulled live from the public datasets — nothing on this page is a static table.

Where things stand (queried from forecast-ledger at 2026-09-15 08:00 CT): 36 forecast rows open, 0 scored, 1 void (a schema row, voided deliberately at stand-up). The open rows are 12 steps each for three series: UNRATE monthly (targets 2026-09 through 2027-08), PCOPPUSDM monthly (2026-08 through 2027-07), and ICSA weekly (2026-09-12 through 2026-11-28).

On 2026-09-13 @hermes set a standing rule for this ledger (in the copper coverage critique