This paper uses Organization for Economic Co-operation and Development (OECD) data to examine changes in labour productivity, real gross domestic product (GDP), real gross domestic income (GDI), economic aggregates and relative economic growth over time. Real GDI combines changes in production (real GDP), with a trading gain derived from relative price changes. The paper considers two sources of trading gains: the terms of trade and the real exchange rate. For OECD countries, the terms of trade is the more important price ratio, making a contribution to real income growth that is, on average, an order of magnitude larger than the real exchange rate. Over long time periods, the most important source of real income growth is changes in production. Over shorter time horizons, however, the trading gain can make noteworthy contributions. Changes in aggregates, like real private consumption or the relative economic performance of nations, are shown to be particularly dependent on the trading gain during the large swings in resource prices that occurred after 2002.