Taxi DriverAlston Mabry writes: "Cab drivers have more opportunities to make money on rainy days, and fewer opportunities on nice, sunny days. So, they should work more hours on rainy days and fewer hours on sunny days."

I have not driven a cab in 35 years, and the last time I drove one in NYC was 1971. Perhaps things have changed since then. If they have not, then the old guys who let me drive their cabs at night for a year would say that Alston was mostly wet. The customers think there are more opportunities to make money on rainy days because they care more about catching a cab. The drivers know that rain turns the traffic into mud, and passengers don't tip for waiting time. A $20 tab from a guy in a decent suit earned $5 if you were rolling; the same tab got you $2 if the guy spent it sitting on the edge of his seat looking at his watch. If you own the cab, then working in the rain is no problem; you get all the revenue, and there is less wear and tear on your kidneys crawling in the rain than racing the lights. If you are a sharecropper with a net net lease (you pay the gas and a mileage fee first, then split the meter takings but get to keep the tips), working in the rain is a loser.

The idea that the different categories of drivers (owner-operators and sharecroppers) might have different incentives seems to have escaped the authors' understanding of how that would affect the data. They also seem to have ignored the Larry Williams factor aka the 80/20 rule - 20% of the drivers make 80% of the net profits. Indeed, they seemed determined to assure that their data sample excludes the people who really know how to drive. On the data from a fleet company they "exclude trip sheets that listed a number of trips that deviates by more than two from the metered number" after noting that "(m)any of the trip sheets were incomplete, since the number of trips listed by the cab driver was much fewer than the number of trips recorded by the meter. Of course, what that means is that the ghost riders - the guys who make gypsy bargains for passengers to ride off the meter — are excluded. I never drove for a fleet company, but the big earners who did were the ones who had more rides than the ones logged by the meter. That possibility of economic behavior seems not to have occurred to the authors.

"[T]here may… well exist better 'scientific' evidence [i.e., empirically demonstrated regularities among 'key' magnitudes] for a false theory, which will be accepted because it is more 'scientific,' than for a valid explanation, which is rejected because there is no sufficient quantitative evidence for it." (Freddy the von, from his Nobel acceptance speech. Full Quote)





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