Why sequential comparisons fail
If imports regularly rise ahead of the school year, a forecast for that period may exceed the preceding summer even when the market is weakening. A sequential comparison can present normal seasonality as acceleration.
Year-on-year comparisons control for much of that recurring pattern. Calendar effects and exceptional events remain, but the comparison answers a more useful question: how does the expected period compare with its closest seasonal equivalent?
The five-year view
One month is noisy. Showing the same calendar month across five years reveals whether a spike is recurring, exceptional or part of a changing pattern.
Hover values should show the amount, currency, flow, reporter, product and month. Users need to inspect the observation behind the line rather than estimate it visually.
The UK series shows why this matters
UK Chapter 92 imports reached £32.7m in October 2024 and £34.6m in October 2025. Those were the highest months in each calendar year. January was far lower at £21.3m in 2024 and £21.5m in 2025. Comparing October with the preceding September would show growth, but comparing October with October reveals the more useful 5.8% year-on-year increase.
The pattern is not perfectly uniform: December 2025 reached £30.2m, materially above December 2024’s £25.3m, while March 2026 fell below March 2025. A five-year seasonal overlay therefore helps distinguish a recurring autumn build from changes in the strength and timing of that build.
The latest UK signal is broad, but uneven
Across the latest trailing year, UK Chapter 92 imports rose 7.1% to £301.7m. Pianos grew 17.8%, wind instruments 11.1%, electronic instruments 8.3%, parts 5.2%, percussion 3.5% and stringed instruments 1.6%.
This breadth supports the interpretation that the aggregate rise is more than one isolated shipment. Yet the spread between categories is large enough that a single market forecast would still be too blunt for a piano manufacturer and a guitar distributor to use in the same way.
Forecast totals, not fragments
A 3-month forecast should show the predicted total across the next three months; 6- and 12-month figures should do the same. Each should compare with equivalent months one year earlier.
Imports and exports need separate forecasts. Adding them can hide a trade-balance change and does not represent market size.
A modelled estimate
Seasonality-aware trend models are a starting point, not a promise. Forecasts should be visibly separate from official observations, with confidence reflecting the amount and stability of evidence.
Sources and scope
This analysis uses official aggregate trade and policy sources. It does not represent retailer sell-through or company-level shipment intelligence. External commentary is labelled separately from official evidence.