Nonresidential investment has been growing rapidly for quite some time – seven straight quarters averaging 10.5 percent growth. We have noted before that this provides powerful evidence that business fear of future regulatory uncertainty seems to be an odd explanation of sluggish economic growth – businesses are, in fact, actually spending pretty quickly during the recovery.

Is it a puzzle that nonresidential investment is coming on two years of rapid growth, yet employment growth remains sluggish? After all, if businesses seem fine in taking on new machines, why aren’t they fine in taking on new staff?

I’d argue the answer to these questions are ‘not really’ and ‘read on.’

First, it’s worth remembering that nonresidential investment just isn’t that big a part of the overall economy – it has averaged 11.1 percent of GDP since 1995 and sits at 10.3 percent today. While it’s nice that it’s performing well, it just doesn’t have enough heft by itself to drive overall trends in either output or employment growth. Contrast this with consumer spending sitting at about 70 percent or more of total GDP.

Second, nonresidential investment is hugely cyclical – from the last quarter of 2007 to its trough in the second quarter of 2009, it fell by 22.4 percent – or about 2.5 times farther than the drop in employment. Today, despite its good growth for nearly two years, it remains well below trend. In fact, Thursday’s report on third quarter GDP shows that the simple level of nonresidential investment remains nearly 8 percent below its pre-recession peak. So, it’s been growing very well for a while now, but it fell extraordinarily far during the recession.

Third, it’s important to remember that, like job-growth, investment has to grow just to keep overall economic slack stable. So, we need roughly 100,000 jobs each month just to keep the unemployment rate stable while absorbing new labor market entrants. And, we need 8 percent of GDP to be invested each year just to keep the overall capital stock from shrinking through depreciation that occurs in the private business sector.

Lastly, it’s worth asking whether investment is now so high after seven straight quarters of growth that it is threatening to change the economy’s capital/labor ratio in an appreciable way. That is, firms invest so that each worker has a useful bundle of capital to work with – one that hopefully grows over time and makes each worker more productive. If investment per worker begins rising well above trend, this could mean that output is just becoming more capital-intensive for some unspecified reason or that firms will have to start soon hiring to stabilize this ratio.

Neither seems particularly likely – investment per worker remains below its 2007 level even as employment shrank over that period. And this means that it remains well below what a simple extrapolation of the pre-recession trend would argue.

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In short, the trend in nonresidential investment is nice, but it won’t by itself bring about a robust recovery. More importantly, it mostly represents simply an ongoing climb out of a steep, recession-induced hole (which should sound familiar) combined with an attempt to run ahead of simple depreciation. And this trend certainly presents no puzzle in that it’s not being accompanied by more rapid hiring.