Recent technological advances and a widening of the wage structure have led many to conclude that technology and human capital are relative complements. The possibility that such a relationship exists today has prompted a widely held conjecture that technology and skill have always been relative complements. According to this view, technological advance always serves to widen the wage structure, and only large injections of education slow its relentless course. A related literature demonstrates that capital and skill are relative complements today and in the recent past (Zvi Griliches, 1969). Thus capital deepening appears also to have increased the relative demand for the educated, serving further to stretch the wage structure. Physical capital and technology are now regarded as the relative complements of human capital, but have they been so for the past two centuries? Some answers have already been provided. A literature has emerged on the bias to technological change across history that challenges the view that physical capital and human capital have always been relative complements. Many of the major technological advances of the 19th century substituted physical capital, raw materials, and unskilled labor for highly skilled artisans (John A. James and Jonathan S. Skinner, 1985). But if physical capital and human skill were not always relative complements, when did they become so, and when did new technology become skilled labor's complement? We argue that capital-skill complementarity was manifested in the aggregate economy as particular technologies spread, specifically batch and continuous-process methods of production. Across the past two centuries, manufacturing shifted first from artisanal to mechanized and nonmechanized factory production, then from simple factories to assembly lines, and finally from assembly lines to continuous and batch processes. Although few products were manufactured by more than two of the technologies mentioned, manufacturing, as a whole, progressed in the fashion described. In considering our argument it is useful to envision manufacturing as having two distinct stages: (i) a machine-installation and machine-maintenance segment and (ii) a production or assembly portion. Capital and educated (skilled) labor, we will argue, are always complements in the machine-maintenance segment of manufacturing, regardless of the technology. Machinists, for example, are needed to install machinery and make it run. The workable capital created by skilled labor plus raw capital is then used by unskilled labor to create the final product in the production or assembly segment of manufacturing. How the adoption of a technology alters the relative demand for skilled workers will depend on whether the machinemaintenance demand for skilled labor is offset by the production-process demand for unskilled labor.

The Legacy of U.S. Educational Leadership: Notes on Distribution and Economic Growth in the 20th Century by Claudia Goldin and Lawrence F. Katz. Published in volume 91, issue 2, pages 18-23 of American Economic Review, May 2001

Genuine change in the economic and social status of U.S. women did not emanate simply from their increased labor force participation but, rather, from their increase in professions and as “career women. ” Those changes first began in the late 1960s and early 1970s. We examine here one factor of momentous importance in this break with the past. The Economist (December 31, 1999) recently named it the greatest science and technology advance in the twentieth century. It is the oral contraceptive, known worldwide by its moniker “the pill.” In 1960 18.4 percent of professionals were women, as were 4.7 percent of “high powered professionals.”1 But in 1998 36.4 percent of professionals were women and 25.1 percent of the “high powered ” subset were. We explore in this article a series of connections that link the birth control pill to the increase of women in professional occupations. Our evidence for the impact of the pill relies largely on the timing of various changes. Changes in laws giving minors certain adult rights and lowering the age of majority enabled young and unmarried women to obtain the pill. Young women’s control over their fertility directly reduced the costs to them of engaging in long-term career investments. The pill also served to increase the age at first marriage and thus indirectly reduced a potential penalty of

The fraction of U.S. college graduate women entering professional programs increased substantially just after 1970, and the age at first marriage among all U.S. college graduate women began to soar around the same year. We explore the relationship between these two changes and the diffusion of the birth control pill ("the pill") among young, unmarried college graduate women. Although the pill was approved in 1960 by the Food and Drug Administration and spread rapidly among married women, it did not diffuse among young, single women until the late 1960s after state law changes reduced the age of majority and extended "mature minor" decisions. We present both descriptive time series and formal econometric evidence that exploit cross-state and cross-cohort variation in pill availability to young, unmarried women, establishing the "power of the pill" in lowering the costs of long-duration professional education for women and raising the age at first marriage.

We explore the first period of sustained decline in child mortality in the U.S. and provide estimates of the independent and combined effects of clean water and effective sewerage systems on under-five mortality. Our case is Massachusetts, 1880 to 1920, when authorities developed a sewerage and water district in the Boston area. We find the two interventions were complementary and together account for approximately one-third of the decline in log child mortality during the 41 years. Our findings are relevant to the developing world and suggest that a piecemeal approach to infrastructure investments is unlikely to significantly improve child health.

We examine whether online learning technologies have led to lower prices in higher education. Using data from the Integrated Postsecondary Education Data System, we show that online education is concentrated in large for-profit chains and less-selective public institutions. We find that colleges with a higher share of online students charge lower tuition prices. We present evidence of declining real and relative prices for full-time undergraduate online education from 2006 to 2013. Although the pattern of results suggests some hope that online technology can “bend the cost curve” in higher education, the impact of online learning on education quality remains uncertain.

We study employers' perceptions of the value of postsecondary degrees using a field experiment. We randomly assign the sector and selectivity of institutions to fictitious resumes and apply to real vacancy postings for business and health jobs on a large online job board. We find that a business bachelor's degree from a for-profit online institution is 22 percent less likely to receive a callback than one from a nonselective public institution. In applications to health jobs, we find that for-profit credentials receive fewer callbacks unless the job requires an external quality indicator such as an occupational license.