Some leaders have more power than others to persuade their followers and make them do what they say. One type of effective leader is a transformational leader. A transformational leader leads people by giving their followers a sense of purpose and a common goal (Chambliss and Eglitis pg. 111). In Milgram's study, the authoritative advocate told the unsuspecting teacher that the purpose of the research was to see whether people learn more effectively when punished. Whenever the teacher doubted his actions, the leader reassured him by saying phrases such as: "... it is absolutely essential that you continue..." (The Milgram Experiment Documentary), which helped to encourage the participant and make him believe that what he was doing was necessary. This is a quality that a transformational leader possesses. Another form of authority that people respect is legitimate authority. Legitimate authority is a type of power recognized as legitimate by those over whom it is exercised (Chambliss and Eglitis page 111). For example, in Milgram's study the authoritative advocate was in charge of a scientific experiment and wore a white lab coat that suggested he was some sort of scientist. This would lead to the assumption that the teacher has credentials. The teacher, therefore, placed his trust in the fact that this leader knew what he was doing and considered his power legitimate