Technological Change and the Stock Market
用模型解释托宾q在1974-1984年间低于1的现象，认为新技术的到来使旧知识和资本过时，导致股市下跌，而国民账户未反映这种快速过时，使q看似低于1。
Tobin's average q has usually been well above 1, but fell below 1 during 1974 – 1984. Our model explains this pattern and reconciles it with unchanging aggregate investment. The stock market value in the numerator of q reflects ownership of physical capital and knowledge, but the denominator measures just physical capital. Therefore, q is usually above 1. Periodic arrivals of important new technologies, such as the microprocessor in the 1970's, suddenly render old knowledge and capital obsolete, causing the stock market to drop. National accounts measures of physical capital miss this rapid obsolescence. Then q appears to drop below 1.