In environmental science, experimental design is an extremely important part of the scientific method. When a scientist seeks to prove or disprove a hypothesis, he or she must carefully design the experiment so that it tests only one thing, or variable.
Borderline personality disorder (BPD), also known as emotionally unstable personality disorder, is a long term pattern of abnormal behavior characterized by unstable relationships with other people, unstable sense of self, and unstable emotions.
Editor's Note: Borderline Personality Disorder (BPD) is a Cluster B personality disorder that is described here (the next document in the center that you were reading). This document that you commented on was Cluster A only, which comprises the first 3 of the 10 disorders.