Garrett M. Petersen

Erdmann, Empiricism, and the Minimum Wage

Erdmann's MW and teen unemployment graph
Pre-trend lines are for period from 27 to 3 months before MW hike. MW Trend lines are for period from 3 month before to 27 months after initial MW hike. [Y axis = Teen Employment To Population Ratio]
Kevin Erdmann, over at Idiosyncratic Whisk, posted a graph similar to the one shown above,* demonstrating that the trend in the US teen employment rate after a minimum wage hike was lower in all but one case than the trend before the hike.

There have been many responses, but I would like to focus on one over at Angry Bear that captures the worst of the criticism.** The writer goes way over the top in criticizing Erdmann, saying that people who oppose the minimum wage “apparently believe that the business cycle never impacts teen employment or unemployment.” To read this article, you’d think think that the only opposition to the minimum wage came in blog-post form. Frankly, no empirical analysis coming from a blog (including Angry Bear) can offer anything but a prima facie case for or against some proposition. I don’t read Erdmann as claiming that his little graph is the final word on the minimum wage.

The Angry Bear post goes on to use some very questionable econometrics to show that the minimum wage doesn’t have a big impact on teen unemployment. The author doesn’t use the inflation-adjusted minimum wage in his graphs (and presumably in his regression) for reasons unknown, making them pretty irrelevant. He then naively regresses the teen unemployment rate against adult unemployment, a recession dummy, the teen population, and the minimum wage to find that (surprise!) the minimum wage doesn’t have a big effect on teen unemployment. For someone who criticizes others about omitted variables, this regression should be pretty embarrassing. That’s time-series data! You don’t just apply OLS regression to time-series data. OLS regression assumes uncorrelated error terms, and the fact that adult (and teen) unemployment last month is highly correlated with adult (and teen) unemployment this month destroys that assumption. Continue reading Erdmann, Empiricism, and the Minimum Wage

Opaque Facts

Welcome to Night Vale

“Some mysteries aren’t questions to be answered, but just a kind of opaque fact—a thing which exists to be not known.” – Welcome to Night Vale: A Story About You

The above quote was in an episode of the excellent podcast Welcome to Night Vale. I love the term “opaque fact,” and it strikes me that economics is full of opaque facts, and that our distinctions between opaque facts and mysteries largely determine our views of markets.

People’s preferences are opaque facts. We can’t know other people’s preferences; the best we can do is observe their past actions to infer something about their past preferences. Continue reading Opaque Facts

Monopsony and the Minimum Wage

Suppose it is entirely true that the employers of low-skilled workers have monopsony power over those workers. Maybe low-skilled workers aren’t informed about their other options.

Standard economic analysis would indicate that under such conditions, the minimum wage could increase employment. However, this standard analysis simplifies the labour contract down to two elements: price and quantity. In a more realistic setting, where labour contracts involve more than just the exchange of some quantity of homogeneous labour for some quantity of money, we would expect other elements of the contract to be adjusted in response to a binding minimum wage.

So what does this mean? Well, without the minimum wage, the employer would compensate his workers so as to minimize his costs for any given level of compensation. He would offer a total compensation package such that the marginal cost of adjusting any element of the package would be equal to the marginal benefit to the employee of adjusting that element of the package. This would minimize the employer’s costs. With a binding minimum wage, the employer is obligated to offer a greater proportion of compensation in cash, so the marginal value of adjusting some other elements of the total compensation package must be higher than the marginal cost of doing so (e.g. the employee would forego $1.50 for $1.00 of additional on-the-job training from his employer). Thus it is more costly to offer any given amount of compensation to employees under a binding minimum wage, and even a monopsonist would reduce his employment of low-skilled labourers! Continue reading Monopsony and the Minimum Wage

Abstaining From Alcohol has Ambiguous Effect on Life Expectancy: Study

Alcohol! I only drink to make YOU more interesting!Can you imagine a news article with that title? Certainly not. How about  this one: Abstaining from alcohol significantly shortens life. There, that’s more sensational, isn’t it? (To be fair, that’s the title on the page, not the title of the article. I’m not sure why they aren’t the same.)

I’ve seen news articles circulating about a recent study from the University of Texas at Austin that followed 1,824 adults between the ages of 55 and 65, and compared how likely they were to die over a 20-year period depending on whether they abstained from drinking alcohol, drank moderately, or drank heavily. The results indicated that moderate drinkers had the  greatest longevity, followed by heavy drinkers, with abstainers being the most likely to die.

This is where the science reporters stopped paying attention, and started writing sensationalist “alcohol is good for you!” news articles.

I’m skeptical of this interpretation. The technique being used by the researchers is one that is very common in health and social science studies, whereby the researcher measures many real-world variables, and uses linear regression to tease out the effects of each variable on the variable under study. Continue reading Abstaining From Alcohol has Ambiguous Effect on Life Expectancy: Study

Introducing the Economics Detective

This blog is about economics. Economics is about people. People are about six feet tall.

What is economics? It’s the science of human action. People have goals, and they employ means to achieve those goals according to their beliefs.  They act.

I will use this blog to explore economics, to discuss current and historical events relevant to economics, and to converse with you, the public, so we can all learn.