Each month through the Bureau of Economic Analysis, Commerce reports the gross domestic product (GDP — basically the total amount of stuff and services Americans produce) for the most recent quarter. There's the first release, which is called the "advance estimate," and then two further estimates that follow.
A recent CNBC analysis showed that the error rate in the second and third estimates have been the same over the past three decades. What's more, the government statistics got the direction of growth wrong about a third of the time. That means that a GDP first estimated to be higher than the previous quarter could in fact be lower.
For that and other reasons, it's often best to look at economic data including GDP growth over a longer period of time. That helps to focus on trends rather than potentially noisy movements in the data. To that end, GDP has increased an average rate of 2.1 percent over the past seven years.
Economist also look at another famous measure of the nation's economy, GDI, which measures the same thing but from the income side. Ideally, GDP and GDI should be equal (after all, if one thing is produced and sold, it's also purchased by another party). But in reality, the two measures are often different — a phenomenon known as "statistical discrepancy" — so the BEA also reports an average of the two figures.