In the course of your research process, you will be confronted with both "good" research and "bad" research. For your purposes, "bad" research is that which is out of date, does not discuss current advances or current trends in the field. To help you evaluate whether a certain piece of research is relevant or not, ask yourself these questions: a) Is this information current? Does it represent the most current thinking in the field?  b) Is this evidence relevant to your argument? Does it offer something new or informative   about your area of study?