It’s obvious that, for many reasons, the size of the global economy is far greater than it was decades ago. We learn in any basic economics course that, over the long run, enhanced productivity and increased technology drive long-term production gains.

Certainly, an economy can produce more widgets if you’re a lean, mean, automated machine… as opposed to a blacksmith with a hammer and forge.

But there are other factors as well. Population growth. Accounting standards. And of course, the continued inflation of the currency. $1 today buys a whole lot less today than it did a century ago, so when comparing, it’s important to find a better standard of measurement.

There are a number of pricing yardsticks we could use… like the cost of a New York City cinema ticket (25 cents in 1935, $20 today). But it would be awkard to calculate GDP in terms of billions of cinema tickets.