Teacher MA attainment rates, 1970–2000

The share of female teachers in the U.S. with an MA more than doubled between 1970 and 2000. This increase is puzzling, as it is much larger than that of other college-educated women, and it occurred over a period of declining teacher aptitude. I estimate the contribution of changes in teacher demographic characteristics, increases in the returns to an MA, and changes in teacher certification requirements to increases in teacher MA attainment rates. I find that the majority of the rise in attainment not attributable to secular trends and increases in the average age of teachers can be explained by increases in the returns to an MA among teachers. The increase in MA returns among teachers presents a second puzzle, as there is little evidence that master's degrees increase teacher productivity.     

Using Story to Help Student Understanding of Gas Behavior

Students tend to have a poor understanding of the concept of gas pressure. Usually, gas pressure is taught in terms of the various formulaic gas laws. The development of the concept of gas pressure according to the early Greeks did not include the concept of a vacuum. It was not for another 2000 years that Torricelli proposed that a vacuum can exist and that he was able to produce a vacuum above a column of mercury. However, the existence of a vacuum continued to be a contentious issue for at least another 100 years. During this time the behavior of gases was studied by Boyle, Amontons, Gay-Lussac, Daniel Bernouli, Charles, and Dalton. In the 19^th century gas behavior was revisited and studied from the molecular level through the work of Graham, Maxwell, Boltzmann, and van der Waal. The stories of conflicting theories and the development of the concept of gas pressure gives students an increased appreciation for the nature of science and helps them with conceptual understanding of the concept of gas pressure.     

The role of educational choice in occupational gender segregation: Evidence from Trinidad and Tobago

We analyse the role of educational choice on the degree of occupational segregation in Trinidad and Tobago during a period in which educational policies intent on equating gender opportunities in education were implemented. To this end we utilize waves of the Trinidad and Tobago labour force survey over the period 1991–2004. Our results show that while educational segregation has fallen substantially over our sample period, this has not translated into less occupational segregation. This suggests that the educational policy has not been sufficient to combat occupational segregation. However, results at a more disaggregated level show that experiences have been heterogeneous across educational and occupational groups.     

Transfers of user process innovations to process equipment producers: A study of Dutch high-tech firms

A detailed survey of 498 high technology small and medium-sized enterprises in the Netherlands shows process innovation by user firms to be common practice. Fifty-four percent of these firms reported developing entirely novel process equipment or software for their own use and/or modifying these, both at significant private expense. Twenty-five percent of the user innovations in our sample were transferred to commercializing producer firms. Many transfers were made without any direct compensation. Very importantly from the perspective of effective diffusion of user innovations, innovations with higher commercial potential - and more general appeal for users - are much more likely to be transferred to producers. The pattern we document of frequent innovation by individual user firms at substantial cost, followed in many cases by voluntary, no-charge information spillovers to producers, suggests that “open source economics” may be a general pattern in the economy.     

“Pyramiding: Efficient search for rare subjects”

The need to economically identify rare subjects within large, poorly mapped search spaces is a frequently encountered problem for social scientists and managers. It is notoriously difficult, for example, to identify “the best new CEO for our company,” or the “best three lead users to participate in our product development project.” Mass screening of entire populations or samples becomes steadily more expensive as the number of acceptable solutions within the search space becomes rarer.The search strategy of “pyramiding” is a potential solution to this problem under many conditions. Pyramiding is a search process based upon the idea that people with a strong interest in a topic or field tend to know people more expert than themselves. In this paper we report upon four experiments empirically exploring the efficiency of pyramiding searches relative to mass screening. We find that pyramiding on average identified the most expert individual in a group on a specific topic with only 28.4% of the group interviewed - a great efficiency gain relative to mass screening. Further, pyramiding identified one of the top 3 experts in a population after interviewing only 15.9% of the group on average. We discuss conditions under which the pyramiding search method is likely to be efficient relative to screening.     

The Dynamics of Chart Success in the U.K. Pre-Recorded Popular Music Industry

In this paper we investigate the dynamics of chartsuccess in the U.K. pre-recorded popular music industryover the period 1980 to 1993 using the British albumchart listings. We find that the incidence of chartsuccess is substantially skewed to the right, whethermeasured by total weeks spent per artist, averageweeks spent per album, or the total number of albumslisted per artist. We subsequently investigatepossible determinants of the length of chart survivalof albums in order to determine what may be drivingthe observed skewness. Our results indicate that thetype of album, seasonal demand, and initial popularityplay an important role in ensuring continued chartlisting of an album.