Visualizing GDP: A Look Inside the Q2 Second Estimate

August 28, 2014

by Doug Short

Note from dshort: The charts in this commentary have been updated to include the Q2 2014 Second Estimate.


The chart below is my way to visualize real GDP change since 2007. I've used a stacked column chart to segment the four major components of GDP with a dashed line overlay to show the sum of the four, which is real GDP itself. Here is the latest overview from the Bureau of Labor Statistics:

The increase in real GDP in the second quarter primarily reflected positive contributions from personal consumption expenditures (PCE), private inventory investment, exports, nonresidential fixed investment, state and local government spending, and residential fixed investment. Imports, which are a subtraction in the calculation of GDP, increased.

Let's take a closer look at the contributions of GDP of the four major subcomponents. My data source for this chart is the Excel file accompanying the BEA's latest GDP news release (see the links in the right column). Specifically, I used Table 2: Contributions to Percent Change in Real Gross Domestic Product.

Click to View
Click for a larger image


Note: The conventional practice is to round GDP to one decimal place, the latest at 4.2. The 4.17 GDP in the chart above is the real GDP calculated to two decimal places based on the BEA chained 2009 dollar data series.

Over the time frame of this chart, the Personal Consumption Expenditures (PCE) component has shown the most consistent correlation with real GDP itself. When PCE has been positive, GDP has usually been positive, and vice versa. In the latest GDP data, the contribution of PCE came at 1.69 of the 4.17 real GDP. The Q2 contribution from PCE increased substantially from the previous quarter.

The latest GDP numbers support the general view that the unusually severe winter was the transitory cause of the Q1 GDP contraction rather than fundamental business cycle weakness.

Here is a look at the contribution changes between over the past four quarters. The difference between the two rightmost columns was addressed in the GDP summary quoted above. I've added arrows to highlight the quarter-over-quarter change for the major components.

As for the role of Personal Consumption Expenditures (PCE) in GDP and how it has increased over time, here is a snapshot of the PCE-to-GDP ratio since the inception of quarterly GDP in 1947. The latest ratio is 68.2%, fractionally below the all-time high of 68.7% in Q1 2011. From a theoretical perspective, there is a point at which personal consumption as a percent of GDP can't really go any higher. We may be hovering in that upper range.

Click to View
Click for a larger image

Let's close with a look at the inverse behavior of PCE and Gross Private Domestic Investment (GPDI) during recessions. PCE generally increases as a percent of GDP whereas GPDI declines. That is not what we've been seeing in recent quarters. Note that I've plotted the two with different vertical axes (PCE on left, GPDI on the right) to highlight the frequent inverse correlation.

Click to View
Click for a larger image

The Third Estimate for Q2 GDP will published on September 26.

Website by the Boston Web Company