- Some grouping ability may create Pareto improvements over uniformly mixed classrooms.
- Contemporaneous behaviors wields stronger influence than peers’ fixed characteristics.
- Obtain very few significant effects of the gender and racial composition variables. But are reluctant to make definitive pronouncements on race and gender effects based on findings.
- Unobserved teacher inputs induce correlated effects on student achievement gains.
- Peer effects operate differently for reading achievement than for math. Peer performance generally has stronger effects on individual achievement in math than in reading, particularly at the elementary school levels.
- Mean exogenous characteristics as well as current average peer performance are found to have significant effects on individual student achievement in a number of circumstances, though results are not very robust.
- Find large and highly significant effects of mean peer achievement gains, at all schooling levels and for both math and reading, among students in the lowest quintile.
- Even in cases where the highest-ranked students experience negative spillovers, as in elementary and high school math, these effects of shifting some high-performance peers to low-performing classrooms not be zero-sum.
- Estimation of peer effects may be sensitive to the inclusion of teacher controls even if individual fixed effects are already included.
- Peer effects are not “one-size-fits-all”, differences in mathematics and reading achievement across schooling levels, depending on whether we allow spillovers from contemporaneous peer outcomes or only from predetermined peer traits, and depending on the ability of the individual student.
- Strong effects from contemporaneous behaviors that cannot be predicted on the basis of fixed peer factors.
- Some externalities on achievement from peer disruption, although they may be either positive or negative.
- Authors are reluctant to make definitive pronouncements on race and gender based on their current findings.