Hi Tae: You have posted this question as an English question but it is actually a statistics question. I am wondering if you are in an English class or a math class.
Anyway; the subject is Quantitative vs Qualitative Data in Statistics;
https://www.youtube.com/watch?v=5rUVYWfZOb8
I would recommend this simple intro video on You Tube that explains the difference of the two.
On your questions; the first question to ask is recidivism of simply going back to prison or perhaps the use of some drug or alcohol then resulting in a trip back to prison.
If you just want to find articles on the topic, I would go to Answer The Public (its free) and type in your subject:
Prison recidivism - causes, etc. and you should get a lot of articles that address the problem that you can use for reference.
Thanks, Courtney W., MA