Understanding this indicator
Copper, oil, agricultural products and other commodities have different supply conditions, but they also respond to a shared economy. Factories need materials, transport uses fuel and investment creates demand for both. When these forces change together, a common movement can emerge beneath the news about individual commodities.
This indicator compares the monthly prices and indices in the commodity sample with a year earlier. Principal component analysis then extracts their strongest shared movement, after adjusting differences in long-term trends and volatility. It is designed to capture the common cycle without allowing one high-priced or unusually volatile commodity to dominate simply because of its units.
The result offers a broad view of commodity price conditions. A rise points to a strengthening common pattern in annual price performance, while a fall points to weakening performance. Demand is one important influence, but supply interruptions, energy costs and exchange rates can also move several commodities together. The indicator therefore shows a market pattern rather than assigning it a single economic cause.
Compare the overall line with individual commodities. Is a rise in oil accompanied by metals, or is energy moving on its own? A broad move carries a different message from a change confined to one part of the market. Pairing the cycle with Commodity Market Structure can help reveal that distinction, while comparisons with manufacturing activity and producer prices connect market prices with the wider economy.
The green line isolates the 3–4-year Kitchin cycle from the historical data; it is a fitted cycle, not a forecast of the next turn. The lower chart shows the 7–10-year Juglar cycle and the 15–25-year Kuznets cycle. Comparing these time scales can reveal why a shorter upswing sometimes sits within a much longer period of weakness. The two main-chart axes use different scales, so compare their timing and direction rather than the height of one line against the other. Historical curves may change as the data are updated.