In the May 1985 issue of the Journal of Operattons Management, we published a paper containing two major segments ). The first segment provtded a comprehensive review of previously published research on unpaced assembly lines. Two of the primary references in this review were path-breaking studies by Hillier and Bohng (1966) and Hillier and Bohng (1979). These studies introduced the idea of the "bowl phenomenon," which suggests that line output can be increased (compared to a balanced line) by unbalancing the line with high service times placed at the beginning and end of the line and low service times placed in the middle of the line. This pair of studies also verified the existence of the bowl phenomenon for exponential and Erlang service times with line lengths up to five stations and buffer capacities between stations from zero to four units.
The second segment of our 1985 paper reported on a set of experiments to investigate the "robustness" of the bowl phenomenon under varying service time and bufter capacity assumptions. We 't~[;texl and confirmed three pnmary hypotheses: l,;rrhe use of the bowl distribution to unbalance an assembly line will not significantly increase the output rate as compared to a balanced configuration when normally-distributed work station service times are employed with less variance than the exponential distribution. 2. Minimal increases of buffer storage capacity will significantly reduce or will negate the benefit of using the bowl distribution. 3. Output rate is not highly sensitive to moderate variations from optimal task time allocation for stochastic unpaced lines.
In other words, we found that the bowl distribution does not have advantages over a balanced line if either more realistic normally-distributed service times are used or larger buffer capaciues are available. Thus the bowl phenomenon, while interesting, does not appear to exist in most real world unpaced hnes.
In the "Note" which immediately precedes this "Reply," the authors take issue with our conclusions, based primarily on their view that our 1985 expenments were "'flawed." While the "Note" authors provide some valuable arguments and correctly point out a weakness concerning the number of simulation repetitions in our 1985 study, in general it is their arguments that are "flawed," as we will