Economists and economic historians want to know how much better life is today than in the past. Fifty years ago economic historians found surprisingly small gains from 19th century US railroads, while more recently economists have found relatively large gains from electricity, computers and cell...

New inventions are good for economic growth, but equally important are improvements in the way we make things - what's known as process innovation. Tim Leunig and Joachim Voth measure the impact of two such innovations - mechanical cotton spinning and the motorcar assembly line - on the world's...