| Abstract: | A number of articles on managerial decision making have addressed the issue of whether or not to round a fractional solution to obtain a solution for a problem involving discrete alternatives. (An example is the problem in which the decision maker must select exactly one of several investment alternatives, but attaches no meaning to selecting two-thirds of one alternative and one-third of another.) Those articles which suggest that rounding can lead to undesirable answers are seemingly supported by the numerous “textbook examples” that purport to illustrate the dangers of rounding. However, the standard examples in which rounding fails to give a workable solution involve only a few rounding possibilities (usually two or four) and do not come from real world applications. Hence, it is questionable whether they provide any insight about what is likely to occur in a practical setting. This note fills a gap in previous discussions of rounding by providing two easily understood examples that dramatically portray the difficulties that rounding can encounter. The first example belongs to an important class of practical problems. We illustrate that rounding fails not only for this example, but also fails for all problems in its class. The second example is a unique “showcase” problem which can be summarized by a 5 times 5 cost matrix. This problem contains more than a million rounding alternatives, all of them infeasible! Following these examples, we present a “rounding paradox” and we show that its resolution gives analytical support to the conclusion that rounding will produce grave difficulties in a wide variety of practical situations. |
