How much history gets rewritten

IMF PortWatch rebuilds its daily series every week, and past values can change. We keep every revision as its own row, so a measured effect names the revision it used. This page counts the revisions we have recorded: how many daily values changed in each pull, how many of those were older than 60 days, and how large the changes were.

By pull

Each row is a day on which we pulled the full PortWatch layers. Our first full pull was in September 2026, so this page covers only the pulls since then.

Daily values revised in each weekly pull, with how old and how large the changes were
Pull date	Values revised	Older than 60 days	Share older	Mean size of change	Changed by more than 10%
2026-09-15	1,880,717	1,842,878	98%	0.51%	9,029
2026-09-22	1,889,634	1,851,684	98%	0.68%	9,785
2026-09-29	1,783,907	1,748,554	98%	0.54%	8,961
2026-10-06	1,896,933	1,860,054	98%	0.51%	7,607
2026-10-17	1,894,463	1,859,521	98%	0.49%	8,550
2026-10-21	1,901,009	1,864,615	98%	0.55%	7,933
2026-10-28	2	2	100%	0%	0
2026-11-10	2,278,551	2,245,715	99%	0.84%	15,674

By series

Daily values revised since our first pull, by series
Series	Values revised	Share older	Mean size of change	Changed by more than 10%
Transit trade volume	2,322	98%	0%	0
Port calls	2,513	50%	28.03%	1,381
Container ship port calls	331	56%	39.55%	173
Dry bulk port calls	536	27%	38.96%	270
Tanker port calls	672	42%	40.86%	428
Estimated export volume	6,634,471	98%	0.63%	34,893
Estimated import volume	6,884,371	98%	0.54%	30,394

Source: IMF PortWatch (portwatch.imf.org), International Monetary Fund, using UN Global Platform AIS data. Statistics derived by World Freight Monitor. Terms. Retrieved 2026-11-10 (10 November 2026).

Counted 2026-11-10 (10 November 2026). Size of change is the absolute difference from the previous revision as a share of that revision, for values that were not zero. Effect method, section 8, explains how a changed value supersedes a published figure.