Knowledge that Transforms

This article presents the first experimental evidence on the effects of live versus Internet media of instruction. Students in a large introductory microeconomics course at a major research university were randomly assigned to live lectures versus watching these same lectures in an Internet setting where all other factors (e.g., instruction, supplemental materials) were the same. We find modest evidence that live-only instruction dominates Internet instruction. These results are particularly strong for Hispanic students, male students, and lower-achieving students. We also provide suggestions for future experimentation in other settings.

This study examines occupational licensing in the United States using a specially designed national labor force survey. Estimates from the survey indicated that 35% of employees were either licensed or certified by the government and that 29% were licensed. Another 3% stated that all who worked in their job would eventually be required to be certified or licensed, bringing the total that are or eventually must be licensed or certified by government to 38%. We find that licensing is associated with about 18% higher wages but that the effect of governmental certification on pay is much smaller.

We analyze the impact of classroom peers' ability (measured by their individual fixed effects) on student achievement for all Florida public school students in grades 3-10 over a 6-year period. We control for both student and teacher fixed effects, thereby alleviating biases due to endogenous assignment of both peers and teachers. Under linear-in-means specifications, estimated peer effects are small to nonexistent, but we find some sizable and significant peer effects within nonlinear models. We also find that classroom peers, as compared with the broader group of grade-level peers at the same school, exert a greater influence on individual achievement gains.

Using original, representative survey data, we document that analytical, routine, and manual job tasks can be measured with high validity, vary substantially within and between occupations, are significantly related to workers' characteristics, and are robustly predictive of wage differences between occupations and among workers in the same occupation. We offer a conceptual framework that makes explicit the causal links between human capital endowments, occupational assignment, job tasks, and wages, which motivate a Roy model of the allocation of workers to occupations. We offer two simple tests of the model's gross predictions for the relationship between tasks and wages, both of which receive qualified empirical support.

Editor's Note Our policy is to annotate all English-language books on economics and related subjects that are sent to us. A very small number of foreign-language books are called to our attention and annotated by our consulting editors or others. Our staff does not monitor and order books published; therefore, if an annotation of a book does not appear six months after the publication date, please write to us or the publisher concerning the book. An Index of Authors of New Books appearing in the Annotated Listings will appear at the end of the General Index in the December issue.

Editor's Note Our policy is to annotate all English-language books on economics and related subjects that are sent to us. A very small number of foreign-language books are called to our attention and annotated by our consulting editors or others. Our staff does not monitor and order books published; therefore, if an annotation of a book does not appear six months after the publication date, please write to us or the publisher concerning the book. An Index of Authors of New Books appearing in the Annotated Listings will appear at the end of the General Index in the December issue.

The categories listed below are used to classify books, book reviews, journal articles, and dissertations indexed in JEL, JEL on CD, EconLit, and www.e-JEL.org . New changes to the classification system appear as soon as possible on www.econlit.org . The JEL classification system may be used freely for scholarly purposes. We suggest the following format: “JEL: A10, B10, etc.”

The categories listed below are used to classify books, book reviews, journal articles, and dissertations indexed in JEL, JEL on CD, EconLit, and www.e-JEL.org . New changes to the classification system appear as soon as possible on www.econlit.org . The JEL classification system may be used freely for scholarly purposes. We suggest the following format: “JEL: A10, B10, etc.”

Editor's Note Our policy is to annotate all English-language books on economics and related subjects that are sent to us. A very small number of foreign-language books are called to our attention and annotated by our consulting editors or others. Our staff does not monitor and order books published; therefore, if an annotation of a book does not appear six months after the publication date, please write to us or the publisher concerning the book. An Index of Authors of New Books appearing in the Annotated Listings will appear at the end of the General Index in the December issue.