What is the effect of the use of the word belief in this statement from the selection: "There's a belief that graduated licensing has led to
a delay"?​

Ambiguity

Explanation:

The word 'Belief' is subjective and based upon one's own reasoning. Using belief in that sentence makes the statement much less credible than if 'It has been proven that' or 'It is a fact that' was used.

This is because using 'belief' means that a certain group of people believe that, and it might or might not be true.