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Reasons for International Changes in the Ratio of Natural Science and Engineering Degrees to the College-Age Population

NSF 09-308 | January 2009 | PDF format. PDF  

By Joan Burrelli and Alan Rapoport[1]

Recent reports have expressed concern that other countries are surpassing the United States in science and engineering education, particularly in the natural sciences and engineering (Freeman 2006, NAS 2006).[2] Data examined for 23 countries/economies where such data are available show that the ratios of first university degrees in natural sciences and engineering (NS&E) to the college-age population have increased substantially in recent decades (tables 1, 2).[3] In 1975 only Japan had a higher ratio than the United States of NS&E degrees per hundred 20–24-year-olds (the college-age population).[4] By 1990, a few of these locations had surpassed the U.S. ratio, and by 2005, nearly all had done so. This report examines the relative influence on this ratio of increasing degree completions, increasing share of NS&E degrees, and the interaction of these two factors. It finds that the rising ratio of NS&E degrees to the college-age population in the locations compared with the United States can primarily be attributed to increased university degree completion, not to an increased emphasis on NS&E education; however, the relative importance of these components varies substantially by location.

TABLE 1.  Population of 20–24-year-olds, all first university degrees, and first university degrees in NS&E, by selected country/economy: 1975, 1990, 2005.

  Table 1 Source Data: Excel file


TABLE 2.  All first university degrees and first university degrees in NS&E per hundred 20–24-year-olds, and NS&E share of all first university degrees, by selected country/economy: 1975, 1990, 2005.

  Table 2 Source Data: Excel file

Components of a Changing Ratio

Although the ratio of first university NS&E degrees to the college-age population has been examined previously (NSB 2004, 2006), these analyses have not tried to differentiate the two components responsible for changes in the ratio over time: increased university degree completion relative to the college-age population and NS&E degrees as an increasing share of all degrees. A change over time in the ratio of first university NS&E degrees to the college-age population can be due to a change in the number of first university degrees relative to the college-age population with no increase in the share of NS&E degrees (referred to here as the university degree completion component), a change in the share of NS&E degrees with no increase in overall degrees relative to the college-age population (referred to here as the NS&E share component), or the interaction of both (referred to here as the interaction component). Each of these components can be positive or negative, but the university degree completion component tends to be positive in almost all cases, whereas the NS&E share component and the interaction component are often negative. This InfoBrief looks at the contribution of these components separately and interactively.

Study Methodology

This study examines the increase in the ratio of first university NS&E degrees to the college-age population from 1975 to 2005 in the United States and 22 other countries/economies where such data are available (listed in tables). It focuses on differences in two periods: 1975–90 and 1990–2005. The analysis does not focus on when the changes actually occurred during the 30-year period examined. Changes between periods in the ratio of NS&E degrees to the college-age population are decomposed into three component parts—the university degree completion component, the NS&E share component and the interaction of both (or interaction component).

The university degree completion component is calculated for each period as follows: the NS&E percentage of total first university degrees in the initial year of the period is multiplied by the ratio of all first university degrees to the college-age population in the final year of the period; the difference between that value and the ratio of NS&E degrees to the college-age population in the initial year is then calculated. This difference represents the change that would result if the NS&E share of degrees remained the same but the number of first university degrees relative to the college-age population changed.

The NS&E share component is calculated for each period as follows: the NS&E percentage of first university degrees in the final year of the period is multiplied by the ratio of all first university degrees relative to the college-age population in the initial year of the period; the difference between that value and the ratio of NS&E degrees to the college-age population in the initial year is then calculated. This difference represents the change that results from only a change in the NS&E share of degrees. The NS&E share component will be positive if the NS&E percentage is higher in the final year of the period than in the initial year and negative if it is lower.

The sum of the university degree completion component and the NS&E component is then compared to the actual change; any difference is the result of the interaction between the two components. The interaction component is the product of the change in NS&E share of degrees and the change in the number of degrees relative to the population and thus represents the change that would result if both the NS&E share of degrees and the number of first university degrees relative to the college-age population changed. The interaction component is negative when the NS&E share of degrees decreases as the number of degrees relative to the college-age population increases.

Values for each component (derived from unrounded data) are shown in table 3. As a concrete example, between 1975 and 1990, the number of NS&E first university degrees per hundred 20–24-year-olds in Sweden increased by 0.19 (from 0.47 to 0.66) and the number of all first university degrees per hundred 20–24-year-olds increased from 2.38 to 2.57. In 1975 NS&E degrees were 20% of all first university degrees. If the share of NS&E degrees did not change between 1975 and 1990, the number of NS&E first university degrees per hundred 20–24-year-olds would have increased to 0.51 (20% × 2.57). The difference between this value and the ratio of NS&E first university degrees to the college-age population in 1975 (0.51 – 0.47 = 0.04) is referred to here as the university degree completion component, which indicates an increase in the ratio of NS&E first university degrees to the college-age population that was due to an increase in the number of degrees in all fields relative to the college-age population.

TABLE 3.  Change in NS&E degrees per hundred 20–24-year-olds and decomposition of components affecting change, by selected country/economy: 1975–1990 and 1990–2005.

  Table 3 Source Data: Excel file

If instead no change occurred in the ratio of all first university degrees relative to the college-age population between 1975 and 1990 but the percentage of NS&E degrees had changed to the 1990 value (25.5%), the number of NS&E degrees per hundred 20–24-year-olds in 1990 would have increased to 0.61 (25.5% × 2.38). The difference between this value and the ratio of NS&E first university degrees to the college-age population in 1975 (0.61 – 0.47 = 0.14) is referred to here as the NS&E share component, which indicates an increase in the ratio of NS&E first university degrees to the college-age population that was due to an increase in the percentage of all first university degrees in NS&E fields.

The interaction component is the remainder of the difference between the actual 1975–90 increase and the sum of the university degree completion and NS&E share components (0.19 – (0.04 + 0.14) = 0.01).

Results

The Period 1975 to 1990

Between 1975 and 1990, the ratio of NS&E first university degrees to the college-age population increased in all 21 countries for which data were available, and in a few countries, the ratio surpassed that of the United States (table 2). The increase in the ratio of NS&E first university degrees to the college-age population was due solely to a university degree completion component (more overall first university degrees per hundred 20–24-year-olds) rather than to an increasing percentage of NS&E degrees in 9 of 21 locations, including the United States (data were not available for China or Portugal in this period). In 11 of the remaining 12 locations, increased university degree completion and an increasing share of NS&E degrees both occurred, with the university degree completion component greater than the increased share of NS&E degrees in 7 of them. Among those in which the university degree completion component was greater, 3 countries (Finland, Ireland, Singapore) had substantial positive (0.1 or higher) interaction components, indicating that the growth in the number of NS&E first university degrees per hundred 20–24-year-olds was due to an interaction between an increase in the number of first university degrees per hundred 20–24-year-olds and an increased NS&E share of those degrees above and beyond the individual components. In only one location (India) among the 21 for which data were available was the increase in the ratio of NS&E first university degrees to the college-age population due solely to an increased share of NS&E degrees. There the university degree completion component was negative (fewer overall first university degrees per hundred 20–24-year-olds). In Italy the decline in the NS&E share of degrees overwhelmed the positive university degree completion component, leading to an actual decline in the ratio of NS&E first university degrees to the college-age population between 1975 and 1990 (table 3).

The Period 1990 to 2005

In 2005 only China and Belgium had a lower ratio of NS&E first university degrees to the college-age population than the United States (table 2). Of the 19 locations with ratios that exceeded that of the United States, the increase in ratio in 10 countries (Denmark, Finland, France, Germany, Greece, Ireland, Japan, Netherlands, Switzerland, United Kingdom) between 1990 and 2005 was due solely to the university degree completion component. In the other 9 locations (Austria, Italy, Norway, Portugal, Singapore, South Korea, Spain, Sweden, Taiwan) the university degree completion component was larger than the NS&E share component (table 3) (data were not available for India in this period). In 6 of these 9 locations, the NS&E share component or the interaction component was substantial (more than 0.1).

Conclusions

The primary explanation for the increase in the ratio of first university NS&E degrees to the college-age population in most of the countries/economies examined was increased university degree completion relative to the college-age population. In both the 1975–90 and the 1990–2005 periods, the university degree completion component was either the only component or the larger component for the majority of countries/economies for which such data were available. Thus, the growth from 1975 to 2005 in the number of countries surpassing the United States in the ratio of NS&E degrees to the college-age population can be attributed primarily to increased university degree completion rather than to an increased emphasis on NS&E education. That is not to say that increased emphasis on NS&E was not an important factor in some countries. The NS&E share component was either the only component or the larger component for five countries in the 1975–90 period and for no countries in the 1990–2005 period. In another eight countries in which the university degree completion component was larger, the NS&E share component was substantial or the interaction component was substantial in either the 1975–90 or 1990–2005 period.

Data Sources and Limitations

The ratio of first university degrees per hundred 20–24-year-olds is an indicator of educational attainment based on two separate sources of data—degrees awarded and population estimates—and can vary with changes in the number of degrees awarded and with changes in the population. The effect of nonsampling error in the degrees and/or population data may alter ratio values and could not be determined. Therefore, rankings may not be precise, small differences in ratios between countries are not meaningful, and the direction of the component in ratios close to zero may vary.

Data on first university degrees in this InfoBrief come from numerous national and international sources, and degrees and degree fields may not be strictly comparable. First university degrees in different countries are of different duration and may not be academically equivalent. First university degrees in this report refers to degrees classified as level 5A in the 1997 International Standard Classification of Education (ISCED), although individual countries use different names for the first terminal degree; for example, laureata in Italy, Diplome in Germany, maitrise in France, and bachelor's degree in the United States and Asian countries/economies. The ISCED classification system changed in 1997, so data on first university degrees from some countries/economies prior to 1998 are not strictly comparable to those for 1998 and beyond.

Population data for most countries are from the Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat. Population estimates were based on the most recent national population censuses updated with data on trends in fertility, mortality, and international migration. These estimates are subject to error from the models used and from the quality of the data. Generally, error is higher for smaller populations than for larger populations. Population data for Taiwan are from the Statistical Yearbook of the Republic of China 2006.

For more information on data and results presented here, please contact Joan Burrelli.

Notes

[1] Joan Burrelli and Alan Rapoport, Science and Engineering Indicators Program, Division of Science Resources Statistics, National Science Foundation, 4201 Wilson Boulevard, Suite 965, Arlington, VA 22230 (jburrelli@nsf.gov; 703-292-7793).

[2] Natural sciences in this InfoBrief are the agricultural; biological; computer; earth, atmospheric, and ocean; physical; and mathematical sciences.

[3] First university degree refers to completion of a terminal undergraduate degree program. These degrees are classified as level 5A in the International Standard Classification of Education 1997 (UNESCO 1997; http://www.unesco.org/education/information/nfsunesco/doc/isced_1997.htm.). See "Data Sources and Limitations" for information on degree comparability.

[4] Actual ranks may vary slightly due to nonsampling error.

References

Freeman, RB. 2006. Does Globalization of the Scientific/Engineering Workforce Threaten U.S. Economic Leadership? National Bureau of Economic Research Working Paper 11457. http://www.nber.org/papers/w11457, accessed 12 June 2008.

National Academy of Sciences (NAS). 2006. Rising Above the Gathering Storm: Energizing and Employing America for a Brighter Economic Future. National Academy of Engineering, Institute of Medicine, Committee on Science, Engineering and Public Policy. Washington DC: National Academies Press.

National Science Board (NSB). 2004. Science and Engineering Indicators 2004. Vol. 1, chap. 2, NSB 04-01; associated appendix tables, vol. 2, NSB 04-01A. Arlington, VA: National Science Foundation.

National Science Board (NSB). 2006. Science and Engineering Indicators 2006. Vol. 1, chap. 2, NSB 06-01; associated appendix tables, vol. 2, NSB 06-01A. Arlington, VA: National Science Foundation.


National Science Foundation, Division of Science Resources Statistics
Reasons for International Changes in the Ratio of Natural Science and Engineering Degrees to the College-Age Population
Arlington, VA (NSF 09-308) [January 2009]


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