Tyler Cowen posts the following graph

and suggests that it is indicative of his Great Stagnation thesis.
However, if we disaggregate the overall stock of capital – which is ultimately what we care about – even a little bit we see three very different trends underlying business investment.
I apologize for the graph quality but the BEA is no FRED. In any case the dark blue line is industrial equipment and has been rising at roughly the same pace over the past 40 years, which means in log terms there has been a steady slowdown as the US deindustrializes. But, of course that is nothing new to any of us.
Transportation equipment – the very light line – is extremely sensitive to the business cycle. It flattens out during the 1980s, reaccelerates in the 90s and then falls off a cliff in the recent recession.
That’s not even investment – that’s the overall stock. The stock of automobiles has been falling since 2007.
On the other hand the yellow line – information processing equipment – has simply exploded as was unaffected by the recession, or any recession for that matter.
The lesson is that what we call fluctuating investment net investment is largely fluctuating investment in transportation. When money is tight or fuel is expensive the stock of transportation equipment in general, and trucks in particular falls. Not, just investment but the actual stock.
While that does represent important losses in economic potential I think its different than what folks have in mind when they conjure up the term “investment.”

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Sunday ~ February 26th, 2012 at 1:27 pm
Lord
These are normailized, but what of the overall levels of these different categories? I assume the rapid growth in IT means it is small overall.
Tuesday ~ February 28th, 2012 at 7:53 am
Disaggregating the investment drought — Marginal Revolution
[...] is a previous post on the investment drought, with another good picture. Karl Smith offers some related remarks, though I do not focus on transportation as he does, rather given his framing I would put more [...]
Tuesday ~ February 28th, 2012 at 1:04 pm
Disaggregating the investment drought — Marginal Revolution | What is investment
[...] is a previous post on the investment drought, with another good picture. Karl Smith offers some related remarks, though I do not focus on transportation as he does, rather given his framing I would put more [...]
Monday ~ March 5th, 2012 at 1:37 pm
Noah Smith on the Great Stagnation « Modeled Behavior
[...] Smith writes Karl Smith claims that the rich-world investment drought is not about "stagnation," it’s about "deindu…Tyler Cowen politely coughs his throat and points out that those are, um, the same [...]
Friday ~ March 9th, 2012 at 8:12 pm
Karl Smith: “The Pretense of Stagnation” | THE DECLINE OF SCARCITY
[...] This is a really important technical argument from Karl Smith about the value of net investment data regarding the Stagnation thesis. It shows that, if you decouple IT investment from transportation and other kinds of investment, IT “has simply exploded [and] was unaffected by the recession, or any recession for that matter.” If American businesses are driving less and computing more, that’s not an argument for stagnation, it’s an argument that computer networks make driving inefficient for a lot of tasks. If a newer technology obtains higher efficiency and gets adopted, how is that not innovation? This entry was posted in Blog, Technological Unemployment by Ted Kupper. Bookmark the permalink. [...]