Having established the relevant fac

Having established the relevant factors and their levels, the next step was to develop hypothetical service bundles by combining attribute levels presented in the above table.
All possible combination of these attribute levels gave rise to a total of 81 (34) possible service bundles for the delivery of automotive parts and 243 (35) bundles for the delivery of consumer goods.
Obviously, these were too many for us to handle effectively.
We therefore applied a fractional factorial design to reduce the number of service bundles to a manageable level while maintaining an orthogonal main-effects design.
Using this design, the numbers of service bundles were significantly reduced to 9 and 16 for the delivery of automotive parts and consumer goods respectively.
These descriptions of trucking service are shown in Tables 5 and 6.