Peer reviews are a very useful but their single biggest drawback is that biasness may come into play. Peers are in direct competition with each other and when one reviews the other’s work, the element of jealousy comes into play and the reviewer may give a bad review just because he/she thinks that other person might get ahead of him. Healthy competition turns into jealousy. In case some one’s work is really bad and the reviewer criticizes it, the person may become angry and try to take revenge from the reviewer and in this way a fair appraisal also leads to other problems. In addition to this friends will try to review each other favorably despite the quality of the work