should handle is 5 4 ¼ 20. The store needs 20 shelves to display that many shirts.
Jeans are sold in 10 waist sizes, in 6 length sizes, from 4 manufacturers. The number of
products that the store should handl e is 10 6 4 ¼ 240. The store needs 240 shelves
to display the jeans. Is this practical?
Note that the number of product differentiating features increases the total number
of product types very fast. The number of the product differentiating features is a
measure of the product complexity. Product complexity is a burden on the
manufacturing system, and may cause assembly errors. Herman Miller, for example,
offers a variety of office chairs. The customer may select the following options: two
(2) height adjustments, three (3) tilt positions, five (5) arm options (including no arms,
two fixed pad finished arms, and two options of adju stable arms), two (2) seat types,
two (2) options of back support, six (6) options of seat finish, six (6) options of back
finish, two (2) chair-base types, five (5) options of casters and glides, 20 fabrics for the
seat, and 20 fabrics for the back. The number of office chair options offered by
Herman Miller is:
2 3 5 2 2 6 6 2 5 20 20 ¼ 17; 280 ; 000
Namely, Herman Miller offers over 17 million product variations. The workers on
the chair assembly line have to handle an enormous product complexity. Moreover,
line rebalancing, required because of frequent volume changes, is a major challenge
for Herman Miller’s operations engineers. However, even with these frequent
rebalancing operations and the large variety, the number of human errors in the
chair assembly process (which is done manually) is small, and the errors are identified
at the inspection station at the end of the assembly line.
In the above example, it is obvious that there is no store that will display 240 types
of pants, because it is not economically justified. If a store tries to handle computers
and sells them off the shelf, the number of computers to be carried is huge (different
memory size, different speed, different hard disks, different built-in accessories, etc.).
Storing a huge number of product variations is absolutely not a cost-effective
marketing strategy. Like the manufacturer, a store must determine the optimal number
of variations that it can handle by looking at it as a tradeoff between customer
satisfaction and store handling costs.
Given that a basic challenge is “how much variety should we offer,” the following
example demonstrates a simple method of calculating the optimal number of
variations in storing products when applying Strategy 1 of mass customization.
5.4.2 Example: Selling Pants in a Store
Imagine that the entire market requires pants of only waist sizes 30–36, and that the
length is irrelevant, since the product can be altered at the store. Assume a sole source
manufacturer of pants, and that v is the number of product variations.
Let us start the analysis by assuming that only waist size 32 is available, that means
an offering of v ¼ 1. Let us assume the distribution model for pants that is depi cted in
Figure 5.8.
ECONOMICS OF PRODUCT VARIATION 137