the temporal limits for explaining your study to a live audience invariably are more restrictive than the time requirements for accomplishing a written presentation of the same study. Put another way, 20 minutes of a listener's time allow you to cover far less than 20 minutes of a reader's time the seasons for this are complex and not all of them are obvious, but the end result is a demand for selectivity in content and economy in delivery. Finally, because the listener is not free to go back and hear must achieve absolute clarity on the first attempt.