By Brock Mutic, Queen’s Economics Department
New research by Queen’s professor Sitian Liu studies the effects that exposure to mass incarceration has on the educational attainment of African Americans in a paper with relevance for policy makers hoping to understand the unintended effects of the criminal justice system in the United States.
In the United States, the educational attainment of black people has historically lagged behind that of white people. Between the 1960s and the mid-1980s, the gap began to close. Since the late-1980s, however, the gap has begun to widen again, with black men experiencing a greater decline in relative educational attainment than black women:
There is a large literature investigating the causes of the convergence that took place between 1960 and the mid-1980s. This literature has found effects due to unequal access to educational resources, and inequalities of parental characteristics, such as parental education and income. Much less is known, however, about why the convergence stopped and began reversing post-1986. One suggestion, proposed by (Evans et. al, 2016), is that the introduction of crack cocaine markets led to the halting, then reversing convergence.
Another factor which may plausibly explain the dynamics of the educational attainment gap between blacks and whites is childhood exposure to mass incarceration. Indeed, when the educational achievement gap began to widen again in the mid-1980s, it was coincided by a rise in mass incarceration. Theoretically, mass incarceration could affect childhood education through family or neighborhood circumstances, or changes in the expected return to education. Considering the effect of exposure to mass incarceration on educational achievement is the focus of new research by Queen’s Economics Department (QED) Assistant Professor Sitian Liu.
Dr. Liu researches the economics of crime and criminal justice. Previously, she has conducted research into the effects of the mass incarceration system on marginalized communities. These research interests into the unintended intergenerational effects of incarceration led her to study the effects the mass incarceration system may have on educational attainment gaps.
Approaching the question of whether and to what extent the dynamics of educational attainment gaps are driven by childhood exposure to mass incarceration, using data from the American Community Survey regarding the period of convergence in educational attainment, Dr. Liu initially noted that high school completion rates increased for black men and women between 1965 – 1986, while they did not change significantly for whites. Therefore, the closing educational attainment gaps seen during that period were mostly driven by increasing attainments for black men and women. Additionally, when the gap resumed widening again in the mid-1980s, this increase too was again mainly driven by the educational attainment of blacks. For this reason, Dr. Liu opted to focus her research on the impacts of mass incarceration on high school completion for African Americans. In order to conduct such a study, data on incarceration rates were thus needed, but such data were not readily available for areas and during the timespan in question. Using a technique she developed in previous research, Dr. Liu first compiled the necessary data by estimating relevant prison population and incarceration rates at the level of metropolitan statistical areas where offenders were sentenced.
With these data in hand, Dr. Liu then used a specification which accounted for whether a student had a high school diploma or GED to estimate the effect of the black male incarceration rate a young black adult was exposed to on their educational attainment path. In principle, this technique produced insights into the effects of exposure to mass incarceration on high school completion.
Separating Causation from Correlation
Determining the extent to which any found correlations existed because of a causal effect of exposure to incarceration on educational attainment is inherently difficult. Measurement errors, or reverse causality—as individuals with poorer educational outcomes could be more likely to take up crime (Lochner and Moretti, 2004)—make assessing causality problematic. Additionally, the large number of potential omitted variables might have interfered with such a causal assessment. For this reason, Dr. Liu needed a way to firmly establish a causal effect from any correlations she discovered. Towards this end, she constructed a novel instrumental variable (IV) which exploited plausibly exogenous changes in sentencing policies across states and over years to hopefully establish causality.
Specifically, the IV she produced “predict[ed] incarceration rates of black men from a metropolitan area using leave-one-out estimates of state-level sentencing outcomes within each crime category, based on a simulation procedure of the prison population”. This method compared two similar juveniles with a positive probability of being arrested; one in a lenient state where the punishment for a crime tended to be a fine, with one in a harsh state where the punishment for the same crime tended to be imprisonment. In this way, the extent to which the different risks of incarceration faced by these juveniles—due to different harshness of their state-level sentencing policies—affected their educational outcomes was estimated, which addressed the issue that different incarceration prospects could be driven by unobservable factors which may independently affect educational outcomes.
Increased Incarceration due to Sentencing Policies
Firstly, Dr. Liu’s research showed that, for almost all types of offences in the contexts studied, punishments became harsher in 2000 as compared to in 1988. Specifically, these punishments became harsher in two senses: people arrested were found to be more likely to go to prison in 2000 than in 1988; and for those who went to prison, their sentences were likely to be longer. This result indirectly suggested that increased incarceration rates were due to sentencing policies becoming more punitive toward almost all types of offenses. This insight is relevant, as it was not found that the increased rates of incarceration were due to people committing more serious crimes than in the past.
Dr. Liu also notably found that after law changes had taken place during the time frame in question, the probability of incarceration conditional arrest for black offenders of drug possession increased significantly. Additionally, by taking a comparative example of two states, it was found that variation in the IV was likely driven by sentencing reforms.
Central Results Reveal Important Effects
Studying the impact of the black male incarceration rate that young black adults were exposed to in adolescence on their high school completion path, Dr. Liu ultimately found that higher incarceration rates due to harsher sentencing policies that young black men were exposed to lowered their likelihood of completing high school. Specifically, it was found that a one percentage point increase in the incarceration rate a young black male was exposed to at age 18 decreased the probability of having a high school diploma or GED by 1.7 percentage points in early adulthood . Overall, the results importantly suggested greater and more robust estimated effects of childhood exposure to mass incarceration on educational attainment in early adulthood for black men than for black women.
Impact of Incarceration at Different Margins
Conceivably, the observed growth in incarceration rates, caused by ‘harsher’ sentencing policies could have been specifically driven by greater tendencies to incarcerate arrestees (extensive margin), or by increasing the length of sentences when someone was incarcerated (intensive margin). At both margins, incarceration could have impacted high school completion. After constructing two IVs to investigate heterogeneity in the effects of incarceration at different margins, Dr. Liu produced results which suggested the uncovered negative effects of black male incarceration an individual was exposed to in adolescence on high school completion were mainly driven by greater tendencies to incarcerate arrestees, at the extensive margin, not at the intensive margin. This was unsurprising to Dr. Liu, among other reasons, due to individuals’ rational response to the expected return to education; sentencing reforms that increase incarceration at the extensive—i.e., increasing the likelihood to incarcerate arrestees—have a greater effect on high school completion than sentencing reforms that increase incarceration at the intensive margin—i.e., increasing the length of sentences. This is because former prisons face great difficulty in reentering the workplace, and thus a higher risk of incarceration at the extensive margin may greatly lower the expected return to incarceration. In contrast, given that a person would be incarcerated, a higher risk of serving longer time in prison may not have a large impact on his future employment perspective.
Insights Provide Relevance for Policy
The question of the broad effects the criminal justice system has had and continues to have in the United States is highly relevant for policy makers; if historic and systemic inequalities are to be overcome, knowledge of the effects of institutions like the mass incarceration system is needed. Previous literature has investigated the ways in which mass incarceration negatively affects communities, and Dr. Liu’s research, finding evidence suggesting that higher incarceration rates due to harsher sentencing policies that young black men are exposed to during adolescence lower their likelihood of completing high school is a highly relevant result. The findings suggest a negative intergenerational effect of mass incarceration for racial minorities. In this way, Dr. Liu’s research is relevant for policy makers hoping to understand and rectify intergenerational effects and systemic inequalities created by an incarceration policy that disproportionately affects marginalized communities. Additionally, the finding that the negative effect of mass incarceration occurred at the extensive margin—i.e., due to a higher risk of entering prison conditional on arrest, not a higher risk of serving a longer time in prison, suggested a potential gain for sentencing alternatives to incarceration for minor crimes, which may be relevant to policymakers hoping to create the best outcomes.
Insights into the Effects of the School-to-Prison Pipeline vs. Exposure to Mass Incarceration
Dr. Liu’s research also suggested that in addition to school expulsion, mass incarceration of adults could also influence young people’s schooling decisions through changes in the expected return to education. Furthermore, the research also suggested that mass incarceration among adults plays a crucial role as a contributing factor to the black-white educational gap in high school attainment. This finding may have policy relevance for the much discussed ‘school-to-prison’ pipeline, suggesting an effect from exposure to mass incarceration, especially for marginalized students.
Informative Research from a QED Economist
Overall, Liu’s research into the effects of exposure to mass incarceration on educational attainment produced informative findings into the potential causes of the black-white educational attainment gap, finding that increased exposure to mass incarceration lowered the likelihood that young black men completed high school. The research’s findings have policy relevance for policymakers hoping to address systemic inequalities and prevent intergenerational effects due to mass incarceration.
Evans, William N, Craig Garthwaite, and Timothy J Moore. (2016). “The white/black educational gap, stalled progress, and the long-term consequences of the emergence of crack cocaine markets.” Review of Economics and Statistics, 98, 832–847.
Liu, Sitian. (2021). “Mass Incarceration and Stopped Convergence in Black-White Educational Attainment”. Queen’s Economics Department. research
 Liu, Sitian. (2020). “Incarceration of african american men and the impacts on women and children.” Available at SSRN 3601259
Lochner, Lance, and Enrico Moretti. (2004). “The Effect of Education on Crime: Evidence from Prison Inmates, Arrests, and Self-Reports.” American Economic Review, 94 (1): 155-189.