A study conducted by a UC Berkeley professor that was published Monday found that individuals sentenced to prison rather than probation were more likely to re-enter the prison system.

David Harding, a UC Berkeley associate professor of sociology, said he worked on the study with his three co-authors for about eight years. Harding and his colleagues collected data from more than 100,000 people who were sentenced for felonies in Michigan between 2003 and 2006. The study focuses on the idea of a prison’s “revolving door,” which it defines as the return of individuals recently released from prison.

The study shows that if people are sentenced to prison rather than probation, the probability of imprisonment in the first three years after release increases by 18 percent among nonwhite individuals and 19 percent among white individuals.

According to Harding, there has been a huge rise in incarceration in the United States since the 1970s. He said he was motivated to conduct the study because he was interested in looking at the consequences of mass incarceration.

“We estimated the first year someone is in prison only reduces the probability of committing (a) new felony by 8 percent,” Harding said. “All the incarceration we’re doing is not preventing crime in the future.”

Harding said the study found that the crimes individuals commit that send them back to prison are not “new crimes” — rather, many of these crimes are parole violations.

The study proposes two possible policy solutions to address this issue. The first proposal is to give parole violators alternative sanctions, as opposed to sending them back to prison. The second policy change the study recommends is to re-evaluate prison sentencing — the study suggests that probation sentences be given more frequently as opposed to incarceration.

“If we aren’t getting crime prevention from putting people in prison (then) maybe we’re sending too many people to prison,” Harding said.

UC Berkeley School of Law professor Franklin Zimring, who is writing a book about mass incarceration, called the study “very plausible.” He added that he also believes that parole violations play a large role in the “revolving door.”

“That revolving door could be slowed if we could improve the experience of prison and the experience of parole afterwards,” Harding said.

Campus fifth-year Adelene Miranda is a member of the campus’s Underground Scholars Initiative, which aims to support formerly incarcerated students in their pursuit of higher education. Miranda — who is also a facilitator for the Teach in Prison DeCal, which sends campus students to tutor inmates at the San Quentin State Prison — said she found the study interesting, but she added that she would’ve liked it to include interviews with people in prison.

Miranda also said she was disappointed the study focused its case studies on the state of Michigan and she wished it had focused on states with higher rates of incarceration. She added that she thought the solutions it proposed were “a good start.”

“There is always going to be this stigma, whether you are on parole or probation or in prison. That stigma is always there and it affects people going back to prison,” Miranda said. “Prison is just a bandage. … I know that prison is not the answer.”

Contact Ella Colbert at [email protected] and follow her on Twitter at @colbert_ella.