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.
Inferences are made by considering three elements: the extent of decision-making, the predictability of behavior, and the outcomes of individual actions. To illustrate, we tend to form more confident judgments about a man who allocates half of his funds to charity than about one who contributes just $5.