Going back at least as far as the landmark 1966 Coleman Report, social scientists and policymakers have debated how much educational achievement gaps reflect the influence of families and social norms on the one hand, and differences in the quality of schools in disadvantaged areas, on the other hand.
As Richard Murnane describes in a recent NBER working paper focused on trends in high school graduation rates, recent research has revealed that academic preparation long before high school substantially accounts for differences in achievement across racial and socioeconomic groups, but it is also important to understand non-schooling factors such as discrimination and opportunity outside of the school setting.
Big Picture Trends
In the early part of the 20th century, the United States led all industrialized nations in high school graduation rates. As best as researchers can tell, the more recent trend in high school completion over the past few decades has been stagnation from the 1970s to the 2000s, a period during which the United States fell behind most European and wealthy Asian countries, and a slight uptick since 2000. The caveat “as best as researchers can tell” is important, because it turns out that defining the true high school graduation rate is non-trivial. One complicating factor is that administrative data from high schools appear to inflate high school graduation rates by, for example, classifying many students who leave before graduation as transfers and then removing them from the denominator of reported graduation rates. Still, by working from multiple surveys and administrative sources, it is possible to derive approximate trends across groups and over time.
Race and geographic segregation are important factors underlying trends in high school graduation rates. Minorities are clustered in disadvantaged urban schools and rural schools in the South. As Murnane points out:
“In 2008, one-half of all high school dropouts attended one of the 1,746 high schools with high dropout rates (in which the number of students enrolled in twelfth grade in a particular year was less than 60 percent of the number enrolled as ninth graders three years earlier). These schools overwhelmingly enroll black and Hispanic students from low-income families. The majority are located in cities, but almost one-third are in rural areas and towns, primarily in the South.”
Sociological and Economic Models of High School Dropout Rates
Sociological explanations often emphasize the contribution of peer groups and friends to dropout rates. In particular, students in schools with high dropout rates are surrounded by friends who may discourage studying, and encourage behaviors like cutting class. These factors are most influential in early adolescence but they set the tone for later achievement by reducing the number of earned course credits and decreasing the normalization of studying behaviors. Students do not want to be picked on for being nerds, a cultural barrier that many charter schools now aggressively try to counteract with pro-school messages in the early grades.
Economic models emphasize a somewhat different set of influences. According to the rational investment model, students make cost benefit analyses about the value of staying in school (considered over a lifetime with some implied discount rate) compared to the best non-school alternative. For example, a coal-mining boom in Appalachia in the 1970s provided an exogenous shock in the rate of low-skilled market wages. There, a ten percent increase in wages decreased the high school graduation rate by 5 to 7 percent. However, this theoretical framework has not held true at the aggregate level: when wages for low-skilled workers have decreased, we have not seen a commensurate increase in high school graduation rates, and vice versa.
Differences in time preferences could also shape the high school dropout decision. Students that value gratification now, versus gratification later may be less likely to persist in high school:
“Students with high estimated rates of time discount were more likely to be sent to the school office for a disciplinary infraction over the next year than students with lower rates of time discount. This is relevant because disciplinary infractions are negative predictors of the probability of high school graduation.”
But where do these time preferences come from? A standard economic model provides no insight into this question, but the burgeoning science of brain development highlights how low-income youth are often under-equipped in early childhood to deal with cognitively demanding tasks. As Murnane points out, time preference is not by itself a sufficient explanation for black-white graduation gaps, because the main factor explaining those gaps is the longer amount of time it takes black students to graduate from high school.
What about interventions?
Murnane has quite a lot to say about the prospects for developing effective interventions to increase high school graduation rates. Interventions during that critical period of early brain development may be one important route to increasing graduation rates. For example, a family support program in Chicago called the Child-Parent Center (CPC) education, increased high school graduation rates by 7.7 percentage points relative to a matched comparison. Comparable effect sizes have not been found in other large national programs, even though there is some encouraging evidence around the Head Start program:
“A significant number of studies provide evidence that public investment in improving education, health, and nutrition during the preschool years is a promising strategy for increasing the probability that economically disadvantaged children graduate from high school. However, important questions remain about the intensity and quality of programs needed to improve long-term outcomes for disadvantaged children.”
What about later interventions? The Tennessee STAR intervention, targeted at reducing class size in elementary school, also appears to have significantly increased graduation rates. One important lesson from Tennessee Star is that multiple investments can be leveraged in different combinations to achieve the same outcome. This should be encouraging since it means that many different paths could lead to reducing high school graduation disparities: increasing teacher quality, reducing class size, and changing peer groups. None of these tasks is simple, and many schools at the front of the education movement today are small-scale laboratories trying to crack this puzzle.