Saturday, July 30, 2016

Trumpian data visualization

Donald Trump just tweeted this chart, designed, I guess, by the graphics folks at Fox News:

I've learned the hard way that averages are dangerous, particularly if time periods differ so much, so I went to the source, the Bureau of Economic Analyses, downloaded the quarterly GDP percent change, and quickly made the following time-series graphic:

The 2007-2009 crisis caused a drastic plunge between the end of George W. Bush's tenure and Barack Obama's first months in office. Right after that, quarterly GDP variation under his presidency doesn't look that different from previous years. Here's the annual data (source):

Another way to approach this story could be to average annual GDP growth under each president. The data is here, and here's the chart (note: I've updated Obama's figure):

The picture becomes a bit clearer now. It shows the recent stagnation described in Robert Gordon's book, summarized in this article (more here and here.) To be brief: economic growth is becoming much harder to achieve, so it is dubious to compare Obama and Bush Jr. to Johnson or Clinton, not to mention to the average of all previous presidents since 1950. And this is just if you accept that the GDP is a good measure of economic development, as Trump does in his tweet. We could argue that other metrics, like the unemployment rate or wage growth, are equally relevant.

The following chart —its source is a good read— provides another depiction of the steady slowdown of economic growth: the shorter the time period you calculate the average from, the smaller the GDP variation is:

Needless to say, I am no economist, so please chime in below if you wish.

UPDATE: Xan Gregg offers this other chart. And here's Catherine Mulbrandon's proposal, which uses GDP per capita.