The theory of planned behavior includes the basic ideas of the theory of reasoned action but adds another important variable to the model. this variable is

This variable is "a person's perception of control over the outcome of the situation".

The theory of planned behavior is a theory which predicts consider conduct, since conduct can be deliberative and arranged. The hypothesis was planned to clarify all practices over which individuals can strive control. The key part to this model is conduct expectation; social aims are affected by the state of mind about the probability that the conduct will have the normal result and the subjective assessment of the dangers and advantages of that result.