An endogenous growth model is developed where each period firms invest in researching and developing new ideas. An idea increases a firm's productivity. By how much depends on how central the idea is to a firm's activity. Ideas can be bought and sold on a market for patents. A firm can sell an...

In 1900 only six percent of unwed females engaged in premarital sex. Now, three quarters do. The sexual revolution is studied here using an equilibrium matching model, where the costs of premarital sex fall over time due to technological improvement in contraceptives. Individuals differ in their...