Throughout the late 1970s and the early 1980s, over 50% of all first-time first-year college
students started in a junior college. Despite such a large role in higher education, we know
relatively little about how well they serve their role of providing an education for all who want to
attend college. Junior colleges affect educational attainment in two ways. First, the schools provide
a place in higher education for those who might not have otherwise attended college, the
democratization qfiecr; however, they also draw away some students who might otherwise have
attended a four-year college, the diversion efiect. The democratization effect is nonnegative;
however the effect of diversion on educational attainment is unclear, a priori, as some students might
be better off starting in a four-year school.
This paper attempts to sort out the overall impact of junior colleges on educational
attainment. I use the natural experiment arising from variation in access to junior colleges across
cities and states to address the problem of self-selection into types of colleges. This approach is
implemented by an instrumental variables strategy in which distance to junior college and average
state two-year college tuition are used to instrument for junior college attendance in an educational
attainment equation. The results suggest that on net junior colleges increase total years of schooling,
but do not change the likelihood of attaining a BA.

This paper tests the hypothesis that compulsory school attendance
laws, which typically require school attendance until a specified birthday,
induce a relationship between years of schooling and age at school entry.
Variation in school start age created by children's date of birth provides
a natural experiment for estimation of the effect of age at school entry.
Because no large data set contains information on both age at school entry
and educational attainment, we use an Instrumental Variables (IV) estimator
with data derived from the 1960 and 1980 Censuses to test the age-at-entry/compulsory schooling model. In most IV applications, the two
covariance matrices that form the estimator are constructed from the same
sample. We use a method of moments framework to discuss IV estimators that
combine moments from different data sets. In our application, quarter of
birth dummies are the instrumental variables used to link the 1960 Census,
from which age at school entry can be derived for one cohort of students,
to the 1980 Census, which contains educational attainment for the same
cohort of students. The results suggest that roughly l0 percent of
students were constrained to stay in school by compulsory schooling laws.