It is hypothesized that the TCI is more closely related to manufacturing lead time performance than the DCI.
o1]: There are no significant differences in the average manufacturing lead time with different TCI values.
a1]: The average manufacturing lead time significantly decreases with the increase of the TCI.
How the common parts are used between end items is hypothesized to affect the manufacturing lead time performance of each individual end item.
o2]: There are no significant differences in average manufacturing lead time with different sources of commonality.
a2]: There are significant differences in average manufacturing lead time with different sources of commonality.
The span of time between the order release and completion is recorded as manufacturing lead time.
Therefore, by controlling the capacity utilization, the experiment ensures that changes in manufacturing lead time are primarily the result of commonality effect.
Future research should verify that similar results can be found regarding the relationship between vendor lead time uncertainty, commonality and manufacturing lead time.
Similarly, to avoid the effects of scheduling on manufacturing lead time, this experiment uses the first-come, first-served (FCFS) scheduling rule.
In short, the focus of the experiment is to investigate the effect of "commonality" and "commonality imbalances" on manufacturing lead time in a realistic environment.
In other words, with zero commonality, variations of the usage of purchased parts does not significantly affect the average manufacturing lead time.