For each combination of bit size and speed, five circuit boards are cut. All 20 circuit boards are selected at random from a lot. The lot comes from a supplier whose production process is in a state of statistical control and whose products consistently meet specifications. All routing is done on the same machine by the same operator. The 20 boards are cut in a random order.
Larger values indicate greater vibration.
The data are given below with the number in parentheses being the run order. Comment briefly on control of outside variables, randomization and replication. Be sure to define the coded predictors explicitly. Predict the values for the four treatment combinations. Construct prediction intervals for each of these values.