Presentation on theme: "1 The Determinants of Research Productivity: A Case Study of Mexico Claudia Gonzalez-Brambila Carnegie Mellon University Advisors: Francisco Veloso and."— Presentation transcript:
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 AgeLife cycle with peak between 40 and 50 GenderWomen publish between 26 to 91% less than men EducationGraduates from top schools, with RA experience and employed in research universities are more productive. Graduates from Grande Ecoles are more productive Cohort effectNo evidence Countries studied United States, France and Israel.
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: 1. Characteristics of the researchers: Age Gender Country where PhD was earned Area and discipline
9 Data Base (cont.) 2. 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 Publications it = F (X it, Z i, c i, u it ) Z i : Stable across time but not across researchers area, gender, country of PhD, cohort X it : varies in both dimensions age, age 2, level in SNI, lagged budget, total number of researchers, total number of publications. c i : individual unobserved effect u it : unobserved effect Method First step: Negative binomial fixed effect model To estimate the parameters of X it Second step: Non linear least square method To estimate the parameters of Z i 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.) Area of Knowledge Researchers are productive between: (years old) Peak of publications per year The peak of productivity is at age: (years old) All29-771.557 Exact Sc.34-821.662 Biol. & Chem.25-832.458 Health Sc.28-78256 Social & Human.35-720.958 Agric. & Biotech33-720.856 Engineering32-701.255 Disciplines Physics34-821.662 Biology25-822.758 Materials Eng29-751.557
14 Comparison with Other Studies (Physics) FactorMexicoUSA (Levin & Stephan) France (Tuner & Mairesse) Peak of publications / year 1.622.9 Decline starts (age) 624552 Women publish (paper on average / year) -0.16--0.9
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 Area of knowledgeProportion of female (%)Gender difference in scientific productivity (paper per year) Exact Sc.15-0.16 Biology & Chemistry36-0.08 Health Sc.39-0.24 Social & Humanities380 Agricultural Sc. & Biotech.220 Engineering120.06
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.