Absence of conflict of interest.
Citation
Brown, V., Carrick, G., Jones, M. R., Pharris-Ciurej, N., Voorheis, J., & Walker, C. (2024). The impact of manufacturing credentials on earnings and the probability of employment. ILR Review, 77(4), 535-561. https://doi.org/10.1177/00197939241256871
Highlights
- The study's objective was to examine the impact of manufacturing industry credentials on earnings and wages, and employment.
- The authors used a matched comparison group design with event-study and difference-in-differences models, using data from the American Community Survey (ACS), the National Association of Manufacturers (NAM), the National Student Clearinghouse (NSC), U.S. Census demographic data, federal administrative tax records, and the Business Register. They used statistical models to compare earnings and employment over time for manufacturing industry credential earners and similar non-credentialed comparison individuals.
- The study found that individuals who earned a manufacturing credential had significantly higher earnings and a significantly higher likelihood of employment after credential attainment than matched comparison individuals without a manufacturing credential.
- The quality of causal evidence presented in this report is moderate because it was based on a well-implemented non-experimental design. This means we are somewhat confident that the estimated effects are attributable to obtaining a manufacturing industry credential, but other factors might also have contributed.
Features of the Intervention
Manufacturing credentials are industry recognized certifications that demonstrate individuals have specific technical competencies needed in modern manufacturing jobs. Individuals earn credentials by completing standardized assessments aligned to competency frameworks set by manufacturing industry bodies, often following related coursework or training but without requiring a degree. The study examined the effects of earning a manufacturing industry credential from one of four organizations: the American Welding Society, the National Institute of Metalworking Skills, the Manufacturing Skills Standards Council, and the Manufacturing Skills Institute.
Features of the Study
The authors conducted a matched comparison‑group study using national administrative data to examine how earning a manufacturing industry credential affects adults’ employment and earnings. The analytic sample includes about 25,000 credential earners—identified in a National Association of Manufacturers–National Student Clearinghouse (NAM-NSC) dataset—and approximately 328,000 matched comparison individuals from the American Community Survey (ACS).
All study participants were aged 20 to 65 and did not have a bachelor’s degree. The treatment condition consisted of individuals who earned a manufacturing credential and the comparison condition consisted of similar ACS respondents who never appeared in the credential dataset and were assigned a pseudo‑treatment year based on their survey year.
The authors linked the NAM–NSC credential records to Census demographic data, federal tax (W‑2) earnings and employment data, and the Business Register, and used event‑study and difference‑in‑differences models to compare outcomes over time between treatment individuals and the matched comparison group.
Findings
Earnings and wages
- The study found that manufacturing credential earners had significantly higher post-credential earnings than comparable non-credentialed individuals, including an estimated earnings difference of about $1,373 in the first year after credential attainment in the matched difference-in-differences model and larger differences several years after attainment in the event-study results.
Employment
- The study found that manufacturing credential earners had a significantly higher probability of employment than comparable non-credentialed individuals after earning their credential (about 0.066 higher in the matched difference-in-differences specification).
Considerations for Interpreting the Findings
The study defines employment as having W-2 earnings on record and treats missing W-2 records as unemployment with zero earnings, which could misclassify some employed individuals who may not appear in W-2 data (for example, the self-employed). The authors also note that their methods may have placed some credential holders in the comparison pool, which could weaken the estimated differences between groups.
Causal Evidence Rating
The quality of causal evidence presented in this report is moderate because it was based on a well-implemented non-experimental design. This means we are somewhat confident that any estimated effects would be attributable to obtaining a manufacturing industry credential, but other factors might also have contributed.