The Effects of Class Size on the Long Run Growth in Reading Abilities and Early Adult Outcomes in the Christchurch Health and Development Study

This paper utilizes the feature of the CHDS data from New Zealand that children are sampled for extremely long individual histories of their class size experiences as well as their scholastic and early labor market outcomes. Our interest is to explore the full set of empirical implications of the recent experimental evidence on class size effects on student achievement from the United States in Project STAR for observational data. We argue that one implication of Project STAR is that only persistent class size reduction policies may have detectable effects, and so the longitudinal aspect of CHDS is necessary to detect class size effects. We account for the observational nature of the CHDS (in that children were not randomly assigned to different class sizes) by examining the long-run trends in test score growth, rather than levels. Consistent with the experimental evidence, we find statistically and economically significant effects of children being assigned to persistently smaller classes on both childhood test score growth as well as on early adult outcomes. Our analysis points the way towards the unification of experimental and observational evidence on class size effects, as well as highlighting several possible pitfalls in the analysis of observational data on this topic.School Quality; Value-Added Model; Experimental Evidence

Inside the 'Black Box' of Project STAR: Estimation of Peer Effects Using Experimental Data

The credible identification of endogenous peer group effects -- i.e. social multiplier or feedback effects -- has long eluded social scientists. We argue that such effects are most credibly identified by a randomly assigned social program which operates at differing intensities within and between peer groups. The data we use are from Project STAR, a class size reduction experiment conducted in Tennessee elementary schools. In these data, classes were comprised of varying fractions of students who had previously been exposed to the Small class treatment, creating class groupings of varying experimentally induced quality. We use this variation in class group quality to estimate the spillover effect. We find that when allowance is made for this 'feedback' effect of prior exposure to the Small class treatment, the peer effects account for much of the total experimental effects in the later grades, and the direct class size effects are rendered substantially smaller.Peer Effects; Data with a Group Structure; Organization of Schooling; Experimental Evidence

Race and School Quality Since Brown vs. Board of Education

This paper presents evidence on the quality of schooling by race and ethnic origin in the United States. Although substantial racial segregation across schools exists, the average pupil-teacher ratio is approximately the same for black and white students. Hispanic students, however, on average have 10 percent more students per teacher. Relative to whites, blacks and Hispanics are less likely to use computers at school and at work. The implications of these differences in school quality for labor market outcomes are examined. We conclude by examining reasons for the increase in the black-white earnings gap since the mid-1970s.

Cavity QED with a Bose-Einstein condensate

Cavity quantum electrodynamics (cavity QED) describes the coherent interaction between matter and an electromagnetic field confined within a resonator structure, and is providing a useful platform for developing concepts in quantum information processing. By using high-quality resonators, a strong coupling regime can be reached experimentally in which atoms coherently exchange a photon with a single light-field mode many times before dissipation sets in. This has led to fundamental studies with both microwave and optical resonators. To meet the challenges posed by quantum state engineering and quantum information processing, recent experiments have focused on laser cooling and trapping of atoms inside an optical cavity. However, the tremendous degree of control over atomic gases achieved with Bose-Einstein condensation has so far not been used for cavity QED. Here we achieve the strong coupling of a Bose-Einstein condensate to the quantized field of an ultrahigh-finesse optical cavity and present a measurement of its eigenenergy spectrum. This is a conceptually new regime of cavity QED, in which all atoms occupy a single mode of a matter-wave field and couple identically to the light field, sharing a single excitation. This opens possibilities ranging from quantum communication to a wealth of new phenomena that can be expected in the many-body physics of quantum gases with cavity-mediated interactions.Comment: 6 pages, 4 figures; version accepted for publication in Nature; updated Fig. 4; changed atom numbers due to new calibratio