Is the death penalty effective?

It is not a new controversial topic that whether the dealth penalty is effective or not, but this topic is still heating up all these years. Some scholars argue that the government should abolish the dealth penalty in which they insist means little to the social security, but others still hold the troditional idea that the death penalty decreases the voilence in society effectively. To me, I'd prefer the formor idea. This topic attracts me because my major in China was law before but I have never do any research about this. So by this chance, I want to study more about the function of the death penalty. I think my interest group would be the law major students and people who interest in politics.