Does stiffer punishment lead to lower crime rates?

I have done some research about the different point of view in the topic. I am to going to start by telling the perspective of the once who believe in it (supporter) and the once who don't (opposers). Then I am telling my point of view and explain why my point of view is right. The question I am answering is an open ended question, so I am going to interpret that stiffer punishment is adult sentences.

First I am going to talk about the supporters. They believe that all youth should be responsible for their actions. Their key arguments are: Stiffer charges will make the youths think twice before they do the crimes; this will lead to lower crime rates in future. Youths who commit crimes are sent to rehabilitation, while sometimes their victims are left to suffer forever. The youth’s age shouldn’t be a bias factor for receiving punishments. The youths should be sentenced as an adult so that they learn from their mistakes. Also, they believe that youths are smart enough to decide what is right or wrong. Next I am to talk about opposers point of view. Their key arguments are: when a youth does something, he doesn’t think twice. This is because their brains are still developing. The youths who commit crimes should be sent rehabilitation, so they do not commit crimes again. Many researchers have come to a conclusion that putting youths in prison with other criminals can effected the mentally, some of those effects turns them into criminals.

Now I am going to talk about my point of view. I personally believe that that should that youths who commit crimes should be sent to rehabilitation instead getting an adult sentence. I believe that this action will not help lower crimes. To support my opinion I will present a research done in New York five years after they decided to make stiffer punishments for youth thirteen and older in 1978 by two criminologists Simon Singer and David McDowell. The criminologist compared the youth crime rates five years before and after