In any given year an estimated 11 million people are booked into US jails, though nobody knows the true number. According to survey data from the Bureau of Justice Statistics, about 70% of jailed individuals have not been convicted of any charges, a proportion which has been rising over time. The decision to incarcerate these individuals, who remain innocent before the law, may have far-reaching consequences. For those incarcerated, being held behind bars may lead to both short-term and long-term economic disruption. For communities, jail incarceration may prevent some crimes from occurring while individuals are in custody, but may also increase post-release criminal activity by even greater magnitudes. Whether jail incarceration provides net social benefits remains a very open and very important question.
Despite the importance of this question, researchers and policymakers don’t know much about who ends up in jail, or what kinds of policies might reduce the harms and increase the benefits from jail incarceration. First, we haven’t had good data on the jailed population, and second, we have lacked reliable analyses of the causal impacts of policies affecting jail incarceration. The Jail Data Initiative, supported by Arnold Ventures, is taking advantage of recent advances in both social science and data science to address both of these gaps and answer important policy questions about jail incarceration.
The initiative, a joint project of the SSRC and NYU’s Public Safety Lab, collects daily person-level data from jails in the approximately 1,300 counties that post their daily jail rosters publicly. Every day, custom-written code crawls through hundreds of local government websites, recording individual-level demographic and booking data about the jailed population. The Jail Data Initiative now stores more than 10 million unique booking records and has over 5 million linked court records. The aggregated data are reported on a user-friendly dashboard and are downloadable; users may also apply for access to the restricted individual-level data. Lead data scientist Orion Taylor, who helped develop the code and has been working on the project since 2019, said that having access to these fine-grained data can open up new opportunities for insight. “Because of the wide differences in the amount and kinds of information reported across counties, jail data can be among the trickiest types of data to work with in criminal justice. We’ve even gotten requests from district attorneys asking if they could get access to the JDI data for their own jurisdictions.”
The complexity of these data also offers opportunities to ask new kinds of policy-relevant questions. Although it is challenging to determine the causal impacts of policy changes on jail incarceration and community safety, Zhaonan Qu, the inaugural Jail Data Initiative postdoctoral fellow, will seek to apply recent methodological advances to tackle this problem. Qu, who received his doctorate in economics at Stanford University in January 2024, was mentored by Nobel laureate Guido Imbens, and specializes in the design of statistical and computational methods to draw causal inferences in precisely this kind of situation.
“I’m particularly excited about leveraging the rich dataset produced by the Jail Data Initiative to help better understand the impacts of criminal justice policies, which could further inform policy-makers on the equity, scalability, and cost-effectiveness of existing and potential policy solutions,” Qu explained recently. In particular, he’d like to find ways to quantify the impacts of stricter bail policies on different population subgroups, the effects of higher fines and fees on incarceration and reoffending, and the longer-term effects of repeated incarceration on social mobility. “Because the initiative offers a broad range of geographical, temporal, and demographic variation, the jail data offers ample opportunities as well as technical challenges for policy-relevant questions.”
Anna Harvey, SSRC President and the founder of the Jail Data Initiative, is looking forward to this new work. “Zhaonan is really the perfect person for this project – even as we speak, there are proposals underway in several states to increase the use of jail incarceration, including increasing the amounts of cash bail that those incarcerated pretrial must post before release. Policymakers have strong opinions about jail incarceration, but not a lot of evidence to inform those opinions. It’s the job of social and behavioral scientists to use all the tools we can to provide them with as much insight as possible, and Zhaonan is at the forefront of knowledge generation in this area. What we learn from his work could inform decisions that affect millions of lives.”
