to measure with a simple line on a graph, but evidence that we live in an age of technological marvels is all around
us—discoveries in genetics and in the structure of particles, the wireless Internet, and other inventions almost too numerous
to count. The U.S. Patent and Trademark Office typically has issued more than 150,000 patents annually in recent years.
This recipe for economic growth—investing in labor productivity, with investments in human capital and technology, as
well as increasing physical capital—also applies to other economies. In South Korea, for example, universal enrollment in
primary school (the equivalent of kindergarten through sixth grade in the United States) had already been achieved by 1965,
when Korea’s GDP per capita was still near its rock bottom low. By the late 1980s, Korea had achieved almost universal
secondary school education (the equivalent of a high school education in the United States). With regard to physical capital,
Korea’s rates of investment had been about 15% of GDP at the start of the 1960s, but doubled to 30–35% of GDP by the
late 1960s and early 1970s. With regard to technology, South Korean students went to universities and colleges around the
world to get scientific and technical training, and South Korean firms reached out to study and form partnerships with firms
that could offer them technological insights. These factors combined to foster South Korea’s high rate of economic growth.
Growth Accounting Studies
Since the late 1950s, economists have conducted growth accounting studies to determine the extent to which physical and
human capital deepening and technology have contributed to growth. The usual approach uses an aggregate production
function to estimate how much of per capita economic growth can be attributed to growth in physical capital and human
capital. These two inputs can be measured, at least roughly. The part of growth that is unexplained by measured inputs,
called the residual, is then attributed to growth in technology. The exact numerical estimates differ from study to study and
from country to country, depending on how researchers measured these three main factors over what time horizons. For
studies of the U.S. economy, three lessons commonly emerge from growth accounting studies.
First, technology is typically the most important contributor to U.S. economic growth. Growth in human capital and physical
capital often explains only half or less than half of the economic growth that occurs. New ways of doing things are