Sources of Error
One of the major sources of error that could have occurred is Paradox error. If any of the values were read from the Mitutoyo or vernier calipers inaccurately, it would result in slight errors in the calculations.

Since the Mitutoyo viewing machine is a very sensitive machine, that greatly magnified the specimen notch , it was difficult to place the specimen so that it was lined up with the machine's cross hairs. Any misalignment of the specimen would result in not dimensions that are incorrect.

During the impact testing with the hammer, the Izods were required to be placed in a specific position  to allow optimal breaking. Any variations in placement of the Izod's could result in inconsistent breaking.