The Determinants of Research Productivity: A Case Study of Mexico

1. The Determinants of Research Productivity: A Case Study of Mexico Claudia Gonzalez-Brambila Carnegie Mellon University Advisors: Francisco Veloso and Granger Morgan

2. Agenda • Introduction • Objective • The Data • The Model • Results • Conclusions

3. Introduction • There is a general consensus that S&T investments enhance economic growth, health, education and security. • However, there is an increased necessity to assess the impact of S&T programs. • This situation has shaped a culture of evaluation and monitoring in research. • Publications and citations are the most common ways to measure the importance of the contributions of a researcher or an organization.

4. Introduction (cont) • Publications play an important role: • To get access to financial resources for research • To recruit and give raises and promotions to scientists • To rank universities’ departments • As a channel of communication with industry • However, there are not many studies that explore the determinants of individual and collective research productivity • Implications for university administrators and policy makers • Forecast the expected productivity of faculty • Design policies to enhance productivity • Parameters to compare researchers across different areas of knowledge and across countries

5. Main Findings of Studies Related to the Determinants of Research Productivity

6. Objective • To explore the determinants of research productivity using a data base of the most productive researchers in Mexico. • Age • Gender • Areas of Knowledge • Cohort • Country of PhD • Level in SNI • Critical Mass • Budget

7. Importance • This is the most comprehensive study of its kind. • Number of researchers • Considers all areas of knowledge • The first outside the developed world

8. Data Base • Information on 14,328 researchers in the SNI from 1991 to 2002. • The data are classified in two categories: • Characteristics of the researchers: • Age • Gender • Country where PhD was earned • Area and discipline

9. Data Base (cont.) • SNI variables: • Level in the system for each year (or no presence) • Budget of Conacyt • Total number of researchers in SNI by area and discipline • Total number of publications by SNI researchers by area and discipline. • The source of publications is the Science Citation Index produced by the ISI. • Publications per year per researcher • Citations per 4 years per publication

10. Number of publications per SNI researcher by year and area

11. The model • Publicationsit = F (Xit, Zi, ci, uit) • Zi: Stable across time but not across researchers • area, gender, country of PhD, cohort • Xit: varies in both dimensions • age, age2, level in SNI, lagged budget, total number of researchers, total number of publications. • ci: individual unobserved effect • uit: unobserved effect • Method • First step: Negative binomial fixed effect model • To estimate the parameters of Xit • Second step: Non linear least square method • To estimate the parameters of Zi • Sample • Researchers with at least one publication between 1991-2001. N=7,793 • To adjust for quality, citations per 4 years. Publications between 1991-1997. N=5,658

12. Results - Age Research Productivity Over the Life Cycle: All Areas of Knowledge

13. Results - Age (cont.)

14. Comparison with Other Studies (Physics)

15. Possible Explanations • SNI encourages researches to continue publishing • The base salary in Mexico is about one third of what researchers actually receive. • Cannot easily be tested because of the lack of an adequate control sample. • The eldest researchers of a research group tend to appear as coauthors in the publications of their colleagues. • Will be tested in future research. • Mexican researchers start and finish their careers some years later than their colleagues in other countries. • There are no systematic differences between those who got their PhD when they were 30 or younger and those who were above 30.

16. Results - Gender • Women publish 0.08 papers less than men on average per year

17. Other Results • Cohort effects • Researchers who got their PhD before 1960 are more productive than the latest educated. • The latest educated are more productive than researchers in cohort 1971-1980 and 1981-1990 • Country of PhD • Researchers who got their PhD in the US or Europe are slightly less productive but graduate when they are younger. • Level in SNI • The big jump in research productivity is seen when researchers change from candidate to level 1. • Critical Mass • Small but positive effect in the total number of publications in the same area of knowledge • Little effect of saturation considering the total number of researchers in the same area of knowledge • Budget • Positive relation between the budget of the previous year and publications

18. Results for citations • The peak of citations per four years is 0.3 and is reached when researchers are 58 years old; this is only one year older than what was found for publications. • Publications of researchers in level 3 receive more citations than any other level. • the most important difference among levels in the program is seen in researchers in Exact Sc. • Health Sc. receive the largest number of citations per four years. • No important difference in what was found with publications

19. Conclusions • The effect of age in research productivity is not very important. • The SNI might have enhanced research productivity until the end of researchers working lives. • Significant differences among areas of knowledge. • The design of public policies could respond to these differences. • There is no important gender gap in research productivity. • Potentially cohort effects.

20. Questions/comments

21. Distribution by Area of Knowledge

22. Mexican Publication in ISI