The Methodology Behind the STEM Index

U.S. News data analysts explain what went into the new STEM Index.

A recent study found that U.S. News has the most stable business school rankings, compared with the Financial Times and Businessweek.

The U.S. News/Raytheon STEM Index measures economic and educational activity in the fields of science, technology, engineering and math dating back to 2000.

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By Matt Mason, Robert Morse and Sam Flanigan

To better understand the roles of science, technology, engineering and mathematics in the United States, it is important to determine whether there has been positive or negative movement in key STEM areas. U.S. News & World Report has developed, with support from Raytheon, an exclusive STEM Index as a tool to track key economic- and education-related STEM activity in the United States over time.

Just like other well-known indexes -- the S&P 500 Stock Index, for example, or the Consumer Price Index -- the U.S. News/Raytheon STEM Index has a base year from which changes in the underlying factors are measured. Our index’s base year is 2000 and was set to equal 100.0. The U.S. News/Raytheon STEM Index is calculated annually by U.S. News and measures the yearly changes in the activity of its components in relation to the year 2000.

The inaugural U.S. News/Raytheon STEM index is not a comprehensive measure of all STEM economic or STEM education activity in the United States and should not be used as a measure to determine if overall STEM goals, such as STEM educational output or STEM economic activity, are being met. It can be considered a snapshot in time of measurements of key indicators of STEM activity. The factors used to compute the overall index can be used to track trends in specific STEM areas.

[SPECIAL REPORT: STEM Index Finds America's Talent Pool Still Too Shallow to Meet Demand]

To develop this index, U.S. News talked with many experts in various STEM fields to determine which data could be used to monitor STEM activity and which fields had reliable information that could be collected and used to build components of the overall index. In order to be included in this inaugural version of the index, a specific STEM measure had to be generally published annually starting in 2000 and had to have enough statistical significance that it provided a credible trend of some important aspect of STEM. The first U.S. News/Raytheon STEM Index relies on data from the U.S. Bureau of Labor Statistics, the National Center for Education Statistics, the College Board, the National Research Center for Colleges & University Admissions, the ACT and the Organization for Economic Co-operation and Development. Just like other widely followed indexes, U.S. News will likely make changes to the weights and components for future indices as more numerous and refined STEM indicators become available.

How the STEM Index Was Calculated

After the STEM information sources were determined, U.S. News gathered thousands of data points including SAT and ACT scores and number employed to create 93 sub-indices. Each sub-index was weighed to compute the eight STEM component areas, which are the variables used to compute the overall STEM Index. Those eight component areas measure changes in STEM employment in the United States, STEM degrees granted at the college undergraduate and graduate levels, interest in STEM at the high school level, performance on the ACT, SAT, Advanced Placement and National Assessment of Educational Progress tests and how U.S. students perform internationally using the Program for International Student Assessments.

How U.S. News data analysts created the STEM Index.
How U.S. News data analysts created the STEM Index.

The final step in the computation of the overall STEM Index was assigning separate percentage weights to each of the eight STEM component indices. The overall STEM Index is the sum of the weighted values of the eight component indices. The highest weights were given to the broadest measures of STEM: STEM employment and STEM degrees granted at the college and graduate level. Those two component indicators, which are reflective of STEM in the economy and the education process, account for 55 percent of the overall STEM Index. The other factors, which relate to education at the K-12 level, account for the remaining 45 percent of the overall STEM Index.

Weights for the components of the STEM Index.
Weights for the components of the STEM Index.

The Eight Component Indices

Employment Index (35 percent of the overall STEM Index): The Employment Index, which has the highest weight in the overall U.S. News/Raytheon STEM index, is an outcome indicator for STEM employment in the U.S. economy. It measures the proportion of STEM jobs in the U.S. by taking the number of STEM jobs divided by the total number of all jobs. In determining how to define STEM employment, we adopted the Office of Management and Budget occupation categories, which include jobs in life and physical science, engineering, mathematics, information technology, social science, architecture and health. The data was collected from the Bureau of Labor Statistics’ Occupational Employment Statistics (OES) program.

Degrees Granted Index (20 percent): Measuring the number of STEM degrees granted to college and graduate students in the United States is an important indicator in forecasting the future of STEM employment. The Degrees Granted Index measures the trend in the proportion of STEM degrees as a share of total degrees by taking the number of STEM degrees granted divided by the number of all degrees granted. This breaks down into STEM associate degrees (20 percent of score), STEM bachelor’s degrees (40 percent) and STEM graduate degrees (40 percent). We relied on the Department of Homeland Security’s STEM-Designated Degree Program List to determine which degrees were in STEM fields. Due to 2013 data not being available as of April 2014, the Degrees Granted Index uses an imputed value for 2013; it is based on the percentage change between 2011 and 2012 for the 2013 STEM index. The data was gathered from the National Center for Education Statistics.