Design of Experiments Guide > Covering Arrays > Example of a Covering Array with Factor Level Restrictions
Publication date: 05/24/2021

Image shown hereExample of a Covering Array with Factor Level Restrictions

This example is patterned after an example described in Dalal and Mallows (1998). An originating phone (Near Phone) calls a receiving phone (Far Phone). Each phone call goes through an interface of type A or B. Five factors are of interest:

Market: USA, UK, Canada, France, Mexico

Near Phone: ISDN, Bus (Business), Coin, Res (Residential)

Near Interface: A or B

Far Phone: ISDN, Bus (Business), Coin, Res (Residential)

Far Interface: A or B

You are interested in which combinations of pairs of these factors are likely to cause failures. However, certain combinations are not possible:

An ISDN line on either phone (Near or Far) cannot use interface A.

Business and Residential lines on the originating phone (Near) cannot use interface B.

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