Monopsony models and the minimum wage

In an interesting and provocative article at Bloomberg Noah Smith discusses recent empirical research that suggests that higher minimum wages do not have negative effects on employment. Smith argues that this work discredits the standard competitive model of labour markets He favours a model of monopsonistic markets where employers have market power. Smith writes,

Together with the evidence on minimum wage, this new evidence suggests that the competitive supply-and-demand model of labor markets is fundamentally broken. If employers have the power to set wages, then not just minimum wage, but other labor market policies -- for example, union-friendly laws -- can be expected to help workers a lot more than popular introductory economics textbooks now predict.

Textbook writers and instructors should respond by changing the baseline model of labor markets that gets taught in class. Students ought to start with a model of market power, in which a few companies set wages below levels found in a competitive market unless prevented from doing so. That model is about as easy to work with as the traditional supply-and-demand setup, but matches the data much better.

Perhaps not too surprisingly not all economists agree with him.

At the EconLog blog, Scott Sumner says he is not convinced by Smith's arguments. Sumner writes,

1. The replication crisis in the sciences, and the social sciences.

2. Conservative studies seem able to explain the very low levels of hours worked in Europe much better than progressive studies. And the studies that Smith cites are progressive studies. That doesn't mean progressives are wrong, but until progressives are able to explain Europe's labor market, I'll continue to have trouble taking them seriously.

3. Most importantly, Smith overlooks the fact that empirical research is just as unfriendly to the monopsony model of labor markets as it is to the competitive model of labor markets. AFAIK, almost all the empirical studies of the minimum wage suggest that higher minimum wages do not come out of profits, but rather are passed on in terms of higher prices. That result is 100% consistent with the competitive model of labor markets, and inconsistent with the monopsony model (which suggests that if employment doesn't fall then product prices do not rise.)

Thus empirical studies show that when a minimum wage increase forces grocery stores to pay higher wages, they pass on the increased costs in the form of higher prices.

Now I suppose that progressives could argue that demand curves don't slope downwards, and that the higher prices will not reduce sales. In that case, a higher minimum wage need not reduce employment. But as soon as you abandon downward sloping demand curves, you are faced with other dilemmas. For instance, why should progressives oppose "regressive" consumption taxes? After all, if demand curves don't slope downwards, then higher prices would not reduce consumption. And since living standards depend on consumption, regressive taxes would not reduce the living standards of the poor.

Of course we know that demand curves do slope downwards, and we know that regressive taxes tend to adversely impact the poor. What we need to figure out is whether higher minimum wages raise prices and reduce sales. So far, the empirical evidence suggests that they do.

To summarize, the empirical evidence on the effect on minimum wages on employment is mixed. The empirical evidence on the effect of minimum wages on prices is pretty clear---it raises prices. That means that, on balance, the empirical evidence is more supportive of the competitive labor market model than the monopsony model.

This doesn't mean that firms have no monopsony power---they almost certainly have some. The question is how much, and whether the short and long run labor demand elasticities differ.

At the Cafe Hayek blog, Don Boudreaux says,

First, as Jim Buchanan, Donald Dewey, and other economists have pointed out, as long as demand curves for outputs are downward sloping, monopsony power is only a necessary and not a sufficient condition for minimum wages not to reduce the employment prospects of low-skilled workers. For minimum wages not to reduce these workers’ employment prospects, employers with monopsony power must also have monopoly power (and not just the sort of such ‘power’ as is identified in models of monopolistic competition). That is, these employers must have the ability to keep the prices of the outputs they sell above average total costs. If they do not have this ability, then there are no excess profits, or rents, out of which the higher labor costs can be paid.

Second, empirical studies typically fail to examine all the many ways that employers and employees can adjust to minimum wages. The list of such possible adjustments other than reduced hours of employment includes reductions in formal fringe benefits (such as paid leave), reductions in informal fringe benefits (such as workplace safety higher than what is minimally required by legislation), and changes in the nature of the jobs such that workers are worked harder in order to produce more output per hour. To the extent that adjustments such as these occur, minimum-wage-induced reductions in employment will be fewer or lower, but the standard textbook model really still holds.

Third, because in the U.S. the national minimum wage has been in place now for 80 years and is at no risk of being repealed, employers have long ago adjusted their business plans – their capital-labor ratios – to the existence of minimum wages. And employers expect occasional minimum wage increases. Therefore, even the finest and most carefully controlled empirical study of a minimum-wage hike today will not detect the employment-reducing effects of the long-standing expectation of minimum-wage hikes. Because employers have already adjusted to the reality of minimum wages – and to the reality of minimum wages being increased from time to time – any study that correctly finds little or no negative employment effect from this or that minimum-wage hike today nevertheless misses the negative employment effects of minimum wages overall.

Fourth, about monopsony power: it’s more difficult to detect than, ironically, standard textbook models suggest. Suppose that Acme, Inc., competes for workers by offering unusually attractive fringe benefits and work conditions. And suppose that Acme, Inc., has a differential advantage over other employers at supplying to its workers such non-wage amenities, or that for Acme, Inc., the marginal cost of attracting X number of workers by supplying non-wage amenities is lower than is its cost of attracting X number of workers by increasing the wages it pays. Under such conditions, Acme, Inc., gains the power to lower its workers wages by some amount without losing all, or perhaps even any, of its workers.

An empirical study of this firm would conclude that Acme, Inc., has monopsony power. But this conclusion would be incorrect, for the ‘power’ that Acme, Inc., is detected to have over its workers is ‘power’ that Acme, Inc., purchased from its workers – workers who voluntarily agreed to Acme’s employment terms.

Put differently, if (as is not unreasonable for many employers) Acme, Inc., values a steady workforce, it can purchase – with non-wage amenities – from its workers the ability to cut their wages without their quitting. The textbook-bound economist, seeing only the reduced wages and no mass exodus of workers from Acme, leaps confidently to the conclusion that Acme has monopsony power. Yet clearly, in this example, that conclusion would be mistaken.

On Twitter, David Neumark, an economist who has spent many years studying minimum wages, wrote,

Strong mischaracterization of the evidence on the #minimumwage https://t.co/Xd5JUXp0ks

— David Neumark (@NeumarkDN) April 5, 2018

Thus, while Smith's position is certainly interesting, and could apply in some particular labour markets, I think he needs to do more to convince many of his fellow economists that the markets with monopsony power should be the standard model for labour markets.