GDP Deflator Real vs Nominal

GDP Deflator: Nominal vs. Real GDP

Of all the price indexes an economy produces, the GDP deflator is the widest, and it comes straight out of the National Accounts. The definition is D = (Nominal GDP / Real GDP) × 100, where the base year is set to 100. Nominal GDP prices output at today's prices; real GDP takes that same physical output and prices it at the levels of a reference year. Dividing one by the other strips everything away except the inflation buried inside the headline GDP growth figure.

Where the IPCA leans on a consumer basket measured by IBGE and the IGP from FGV puts most of its weight on the wholesale side, the deflator reaches every final good and service made at home: consumer goods, capital goods, government services, exports. In method it sits closer to a Paasche index, since the weights shift along with whatever the actual consumption mix happens to be in each period. In Brazil it lands every quarter from IBGE alongside the Contas Nacionais Trimestrais, and FGV/IBRE adds commentary that the market pays attention to. Because the deflator follows the full output basket, central banks keep an eye on it to see whether the headline CPI is letting price pressure on investment goods or exports slip by unnoticed.

Applications

People reach for the deflator to turn nominal series into real ones, like real wages or real GDP per capita. It also helps estimate real GDP growth in the window when only nominal numbers have come out, and it serves as a sanity check against the CPI whenever economists start to doubt that the consumption basket still represents what's actually being bought. Analysts go a step further and build deflators for individual sectors, services or government consumption, say, to dig into how relative prices move inside the economy.

FAQ

Why does the deflator usually differ from the IPCA? The IPCA follows a fixed consumer basket, while the deflator takes in the whole of GDP, capital goods and exports included. A commodity boom or a swing in the investment cycle is enough to pull the two apart.

Can the deflator be negative? It can. During deflation, or when the terms of trade collapse, the deflator falls, which is its way of saying that average output prices came in lower than a year earlier.

How is real GDP recovered from the deflator? Flip the formula around: Real GDP = Nominal GDP / (D / 100). That's the same step IBGE runs behind the scenes before it puts out the growth rates.