This article investigates patent protection for a long sequence of innovations where firms repeatedly supersede each other. Incentives for R&D can be insufficient if successful firms earn market profit only until competitors achieve something better. To correct this problem, patents must provide...

We study response behavior of New York City parking-ticket recipients by analyzing administrative data on 6.6 million tickets issued to 2 million individuals over two years. Exploiting variation (from a policy change and a field experiment) in letters sent to recipients, we find that forgetting...

Despite average per-capita consumption of roughly $1 per day, many Tanzanian households do not take advantage of bulk discounts for staple goods. Using transaction diaries covering nearly 57,000 purchases by 1,499 households over two weeks, we find that through bulk purchasing the average...

Despite average per-capita consumption of roughly $1 per day, many Tanzanian households do not take advantage of bulk discounts when buying staple goods. Using transaction diaries covering nearly 57,000 purchases of 22 items by 1,499 households, we quantify the financial loss incurred (and the...

We investigate heterogeneity in responsiveness to reminder letters among New York City parking-ticket recipients. Using variation in the timing of letters, we find a strong aggregate response. But we find large differences across individuals: those with a low baseline propensity to respond to...

Do poor households shop in a way that leaves money on the table? A simple way to maximize consumption, conditional on available cash, is to avoid regularly purchasing small amounts of nonperishable goods when bulk discounts are available at modestly larger quantities. Using two-week transaction...