Fiedler's leadership contingency model measures a leader's style using a least preferred coworker questionnaire. The model assumes a leader's style is fixed. Research uncovered three key situational factors that determine leader effectiveness: leader-member relations, task structure, and position power. Reviews of studies testing the model provided considerable evidence supporting it. Situational leadership theory focuses on followers' readiness and prescribes leadership styles ranging from telling to delegating based on the situation.