How to read GDP reports in the US and Canada

What GDP measures and when it comes out

GDP is the total value of goods and services produced in an economy over a period. In the US, the Bureau of Economic Analysis (BEA) publishes it each quarter at 8:30 AM ET. Each quarter is reported three times as more data arrives.

The advance estimate comes roughly a month after the quarter ends and gets the most attention because it is the first look. The second and third estimates follow in the next two months and revise the figures. Larger annual revisions can later change the picture again, so an early number is a best guess at the time it is published.

• Advance estimate: first read, built with incomplete data.
• Second estimate: updated with more complete source data.
• Third estimate: further refined, and usually draws less market attention.

Real growth and the annualized rate

The headline US figure is real GDP, meaning it is adjusted for inflation so it reflects changes in volume. Nominal GDP is the version measured in current dollars, before that adjustment.

US growth is shown as a seasonally adjusted annualized rate. This takes the change from one quarter to the next and expresses what it would be if that pace continued for a full year. Annualizing makes quarters easier to compare with annual figures, but it also magnifies small quarterly moves. A modest shift in one quarter can look large once annualized.

The report also includes price measures, such as the GDP price index and PCE prices for the quarter. Traders who follow inflation often read these alongside the growth number.

The main components

GDP is usually broken down by spending. The basic identity is: consumer spending plus investment plus government spending plus net exports. Each piece tells a different story about where demand is coming from.

Consumer spending is the largest component in the US, so changes in household demand carry a lot of weight. Investment includes business spending on equipment and structures, home building, and changes in inventories.

• Consumer spending: household purchases of goods and services.
• Investment: business equipment, structures, intellectual property, residential construction, and inventory changes.
• Government: federal, state and local spending on goods, services and investment, excluding transfer payments such as Social Security.
• Net exports: exports minus imports.
• Inventories: the change in the stock of goods businesses hold, counted within investment.

Why inventories and trade swing the headline

Inventories and net exports can move a lot from quarter to quarter without saying much about underlying demand. If businesses stock up ahead of expected tariffs or a supply problem, inventories rise and add to GDP. When they draw those stocks down later, the same effect subtracts from growth.

Trade works in a similar way. Imports are subtracted in the GDP calculation, so a surge in imports, perhaps to beat a policy change, can pull the headline down even when domestic buying is solid. These swings often reverse the following quarter.

To filter out this noise, many analysts watch final sales to private domestic purchasers. It combines consumer spending and private fixed investment, leaving out inventories, trade and government. It is often read as a cleaner gauge of private demand.

Why markets often care more about the details

Markets have tended to react to how GDP compares with expectations, and the headline is only the starting point. A strong headline driven by inventory building can be read as weaker than it looks. A soft headline caused by an import surge, with healthy consumer spending underneath, can be read as firmer.

Context also matters. GDP covers a quarter that has already ended, and other data released earlier has often shaped expectations. A big surprise in the price measures can draw more attention than the growth figure, especially when inflation is the market's main concern. Reactions vary, and exceptions are common.

• Which components drove the change in the headline?
• Did final sales to private domestic purchasers tell a different story?
• Were prior quarters revised up or down?
• Did the price measures surprise relative to expectations?

Reading Canada's GDP

Statistics Canada publishes GDP both monthly and quarterly, with releases at 8:30 AM ET. The monthly report measures output by industry, such as manufacturing, mining and services. It usually includes a flash, or advance, estimate for the following month, which offers an early hint of direction.

The quarterly report is based on expenditures and follows the same broad structure as the US: household consumption, business investment, government, inventories and trade. Canada's quarterly growth is also commonly quoted at an annualized rate. Because Canada is a large exporter of energy and other resources, trade and commodity sectors can have a noticeable effect on the figures and on how the Canadian dollar and Canadian assets respond.

Key terms

Real GDP

Economic output adjusted for inflation, so it reflects changes in volume rather than prices.

Annualized rate

A quarterly change expressed as the yearly pace it would reach if it continued for four quarters.

Advance estimate

The BEA's first published estimate of quarterly GDP, based on incomplete data and revised later.

Final sales to private domestic purchasers

Consumer spending plus private fixed investment, a measure that excludes inventories, trade and government.

Inventory investment

The change in goods businesses hold in stock, which adds to GDP when stocks build and subtracts when they shrink.

Net exports

Exports minus imports, so rising imports lower GDP in the calculation.

GDP price index

A measure of price changes across all goods and services counted in GDP.

Flash estimate

Statistics Canada's early estimate of the next month's GDP, published with the monthly report.