Class Size and Class Heterogeneity

Abstract

We study how class size and class composition affect the academic and labor market performance of college students, two crucial policy questions given the secular increase in college enrollment. Our identification strategy relies on the random assignment of students to teaching classes. We find that a one standard deviation increase in class-size results in a 0.1 standard deviation deterioration of the average grade. Further, the effect is heterogeneous as it is stronger for males and lower income students. Also, the effects of class composition in terms of gender and ability appear to be inverse U-shaped. Finally, a reduction of 20 students (one standard deviation) in one's class size has a positive effect on monthly wages of about 80 Euros (115 USD) or 6% over the average.

Ability Peer Effects in University: Evidence from a Randomized Experiment

“…The first exploits naturally occurring variation in peer group composition (f.e. Hoxby 2000;Carrell et al 2009;Ammermueller and Pischke 2009;De Giorgi et al 2012;Feld and Zölitz 2014) and a second, smaller, and more recent literature uses randomized experiments (Duflo et al, 2011;Carrell et al, 2013). While results are highly context dependent, the literature generally finds that peer effects are nonlinear and heterogeneous.…”

The Academic and Labor Market Returns of University Professors

“…This effect is smaller but comparable to the findings in Carrell & West (2010), who estimate an increase in GPA of approximately 0.052 of a standard deviation for a one standard deviation increase in teaching quality. To further put the magnitude of our estimates into perspective, it is useful to also consider the effect of a reduction in class size, which has been estimated by numerous papers in the literature (Joshua D. Angrist & Victor Lavy 1999, Krueger 1999, Oriana Bandiera, Valentino Larcinese & Imran Rasul 2010 and also on the same data used for this study (De Giorgi, Pellizzari & Woolston 2012). The estimates in most of these papers are in the range of 0.1 to 0.15 of a standard deviation increase in achievement for a one standard deviation reduction in class size, thus about two to three times the effect of teachers that we estimate here.…”

“…16 The standard random effect transformation subtracts from each variable in the model (both the dependent and each of the regressors) its within-mean scaled by the factor θ = 1 − features, both observable and unobservable, that are fixed for all students in the class. These certainly include teaching quality but also other factors that are documented to be important ingredients of the education production function, such as class size and class composition (De Giorgi, Pellizzari & Woolston 2012).…”

“…3 De Giorgi, Pellizzari & Woolston (2012) use data for these later cohorts for a study of class size. 4 The other degree programs were Economics and Social Disciplines, Economics and Finance, Economics and Public Administration.…”

Understanding Peer Effects: On the Nature, Estimation, and Channels of Peer Effects

“…In the context of post-secondary education, a number of studies address the selection problem by exploiting exogenous assignment of students to sections (Booij et al, 2015;De Giorgi, Pellizzari, & Woolston, 2012), dorm rooms (e.g., Brunello, De Paola, & Scoppa, 2010;Sacerdote, 2001;Zimmerman, 2003) and living communities in military colleges (Carrell et al, 2009;Carrell et al, 2013;Lyle, 2007). Linear-in-mean point estimates in these environments are typically small and positive or statistically insignificant.…”