Chetty, Friedman, and Rockoff (2014a, b) study value-added (VA) measures of teacher effectiveness. CFR (2014a) exploits teacher switching as a quasi-experiment, concluding that student sorting creates negligible bias in VA scores. CFR (2014b) finds VA scores are useful proxies for teachers' effects on students' long-run outcomes. I successfully reproduce each in North Carolina data. But I find that the quasi-experiment is invalid, as teacher switching is correlated with changes in student preparedness. Adjusting for this, I find moderate bias in VA scores, perhaps 10–35 percent as large, in variance terms, as teachers' causal effects. Long-run results are sensitive to controls and cannot support strong conclusions.

Teacher contracts that condition pay and retention on demonstrated performance can improve selection into and out of teaching. I study alternative contracts in a simulated teacher labor market that incorporates dynamic self-selection and Bayesian learning. Bonus policies create only modest incentives and thus have small effects on selection. Reductions in tenure rates can have larger effects, but must be accompanied by substantial salary increases; elimination of tenure confers little additional benefit unless firing rates are extremely high. Benefits of both bonus and tenure policies exceed costs, though optimal policies are sensitive to labor market parameters about which little is known.

School choice policies promise to align the incentives of school administrators with the demands of parents, and may therefore lead to more efficient educational production (Milton Friedman 1962; Geoffrey Brennan and James Buchanan 1980; John Chubb and Terry M. Moe 1990). Absent a large-scale school voucher program in the United States, however, this prediction has been difficult to test. Several authors (e.g., Melvin V. Borland and Roy M. Howsen 1992; Clive R. Belfield and Henry M. Levin 2002) have suggested studying the effects of choice, the use of the residential location decision to select among local monopoly education providers. The idea here is that fragmented governance induces competition among school districts analogous to that which would occur among schools with nonresidential choice. In an influential paper, Caroline M. Hoxby (2000) points out that current governance structures are potentially endogenous to school productivity, and proposes that variation in topography, which may have influenced optimal jurisdiction size before modern transportation technologies, provides a source of exogenous variation. She estimates instrumental variables regressions of individual test scores and school spending on a metropolitan-level Tiebout choice index, defined as one minus a Herfindahl concentration index with districts' enrollments as their market shares, using as excluded instruments the number of larger and smaller streams in the area. She reports substantial positive effects of district fragmentation on student test scores and negative effects on spending. This Comment presents a reanalysis of Hoxby's test score results, which form the core of her empirical analysis. These results turn out to be quite sensitive to plausible alterations to Hoxby's specification. In particular, the large, significant effect of choice on achievement obtains

In a multicommunity model, high-income families cluster together in any equilibrium, and cluster near effective schools if effectiveness is an important component of community desirability. Governmental fragmentation facilitates this residential sorting. Thus, if parents prefer effective schools, income correlates with effectiveness in high-choice-market equilibrium. I examine the distribution of student background and test scores across schools within metropolitan areas that differ in the structure of educational governance. I find little indication of the “effectiveness sorting” that is predicted if parents choose neighborhoods for the efficacy of the local schools. This suggests caution about the productivity implications of school choice policies.

Unemployment Insurance benefit durations were extended during the Great Recession, reaching 99 weeks for most recipients. The extensions were rolled back and eventually terminated by the end of 2013. Using matched CPS data from 2008-2014, we estimate the effect of extended benefits on unemployment exits separately during the earlier period of benefit expansion and the later period of rollback. In both periods, we find little or no effect on job-finding but a reduction in labor force exits due to benefit availability. We estimate that the rollbacks reduced the labor force participation rate by about 0.1 percentage point in early 2014.