Alchian–Allen effect

The Alchian–Allen effect was described in 1964 by Armen Alchian and William R Allen in the book University Economics (now called Exchange and Production[1]). It states that when the prices of two substitute goods, such as high and low grades of the same product, are both increased by a fixed per-unit amount such as a transportation cost or a lump-sum tax, consumption will shift toward the higher-grade product. This is because the added per-unit amount decreases the relative price of the higher-grade product.

Suppose, for example, that high-grade coffee beans are $3/pound and low-grade beans $1.50/pound; in this example, high-grade beans cost twice as much as low-grade beans. Now add a per-pound international shipping cost of $1. The effective prices are now $4 and $2.50; high-grade beans now cost only 1.6 times as much as low-grade beans. This reduced ratio of difference will induce distant coffee-buyers to now choose a higher ratio of high-to-low grade beans than local coffee-buyers.

The effect has been studied as it applies to illegal drugs and it has been shown that the potency of marijuana increased in response to higher enforcement budgets,[2] and there was a similar effect for alcohol in the U.S. during Prohibition.[3] This effect is called iron law of prohibition.

Another example is that Australians drink higher-quality Californian wine than Californians, and vice versa, because it is only worth the transportation costs for the most expensive wine.[4]

Colloquially, the Alchian–Allen theorem is also known as the “shipping the good apples out” theorem (Thomas Borcherding),[5] or as the “third law of demand.”[6]