What is Tokyo Core YoY?
Tokyo Core YoY is the year-on-year rate (change versus the same month last year) for Tokyo's 2020-base fixed-basket Consumer Price Index. Core means all items less fresh food (fresh fish, vegetables and fruit); core-core (a deeper underlying gauge) also strips energy (electricity, gas and fuel). Japan's Statistics Bureau publishes it for Tokyo's 23 wards only, as an early leading indicator covering services like school fees, rent and eating out. It is not a cost-of-living index and excludes taxes, savings and property purchases, while, unlike United States core, energy stays inside core.
When is it released and what happens each release?
Prices are collected Wednesday to Friday in the week containing the 12th, with perishables (fresh fish, vegetables, fruit and flowers) priced 3 times monthly. Tokyo mid-month preliminary values (early, not draft) are released at 8:30 AM Japan time on Friday of the week including the 26th. The same morning brings prior-month national results, a CPI report and full tables on e-Stat, with year averages in December and fiscal averages in March. Monthly indices are final on release; adjusted figures are revised each December and published rates are never recalculated.
What moves Tokyo Core YoY?
Core moves with processed food, housing, energy and goods, while fresh food stays out for its volatility.
- Food less fresh food, 21.44%: Covers processed food, eating out, dairy, oils, meat and drinks, the largest driver block.
- Housing including imputed rent, 27.6%: Covers rent and imputed rent for owner-occupied homes, a slow-moving stabilizer.
- Fuel, light and water charges, 5.55%: Covers electricity, gas and water bills, holding the 4.7% energy component where subsidies hit first.
- Furniture and household utensils, 3.35%: Covers durable home goods sensitive to goods inflation.
- Energy, 4.7%: Covers electricity, city gas, propane, kerosene and gasoline, the main swing component.
- All items less fresh food and energy, 91.45%: Tracks underlying inflation after stripping energy; read it with core to see through temporary subsidies.
The March 3, 2023 release for February shows the split: headline rose 3.4% (January: 4.4%) and core rose 3.3% (January: 4.3%). Core-core accelerated to 3.2% (January: 3.0%), so headline and core each slowed 1.0 point while underlying inflation quickened. Energy fell from 26.0% to 5.3%, cutting 1.07 points, as electricity dropped to -1.7% on the government relief programme and gasoline reached -2.2%. Processed food rose from 7.4% to 7.8% and durables from 10.6% to 14.4%, while core fell 0.7% but core-core rose 0.3%: read both gauges together.
How is Tokyo Core YoY calculated?
- Item index: Divide the month's average price by the 2020 base-year average and multiply by 100; a ¥100 item at ¥103 scores 103.0.
- Aggregation with fixed weights: Average item indices up the tree using base-year spending weights; fresh food uses monthly weights instead. Weights come from the household spending survey and prices from the retail price survey; the base year equals the weight reference year.
- Missing prices and quality change: Carry forward the last price for off-season items and adjust quality gaps by overlap, class-mean or hedonic methods. Electricity and mobile charges use typical-usage model formulas, not raw tariff quotes.
- Year-on-year rate: Take the comparison-month index minus the same-month prior-year index, divide by the prior-year index and multiply by 100. Use unrounded indices; 103.7 over 100.4 gives 3.3%.
- Contributions: Split the headline move into percentage-point contributions that sum to the total within rounding.
- Base year and linking: The base and weight reference year is 2020, averaging 2019 and 2020 spending to dilute the pandemic distortion. Series link across the 5-year rebasing, and published rates are never recalculated.
- Seasonal adjustment: The X-12-ARIMA method serves monthly readings only; the year-on-year rate needs none.
Key point: Tokyo Core strips only fresh food; energy stays inside, so do not confuse it with United States-style core excluding food and energy.
