People make inferences on the basis of three factors; degree of choice, expectedness of behavior, and effects of someone's behaviors. For example, we believe we can make stronger assumptions about a man who gives half of his money to charity, than we can about one who gives $5 to charity.
When forming judgments, people consider the degree of choice, the expectedness of behavior, and the effects of actions. Thus, we are more likely to make stronger assumptions about a man who gives half his money to charity compared to one who contributes just $5.