In a study of factors that affect the ability of the laser in a DVD player to read the information on a DVD, a researcher decides to examine several different photoresist thicknesses used in making the plates from which plastic DVDs are stamped. As a response variable, the researcher decides to measure the average pit depth of the holes etched on the surface of the DVD. The experiment must be conducted under a fixed budget and time constraint that allows the researcher to analyze a sample of at most 20 DVDs. Required:
a. Suppose that it is known that, for any fixed photoresist thickness, there tends to be little, if any, variation in the pit depths on a DVD Which would be better: (1) an experiment with little or no replication and several pho- toresist thickness levels or (2) an experiment with more replication, but fewer photoresist thickness levels?
b. Suppose it is known that, even for a fixed photo- resist thickness, pit depths can vary substantially Answer the question posed in part (a) for this situation.