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When designing a decision table, it is often worth considering in which order the different conditions (rows) should be declared. To illustrate this, see the two semantically equivalent decision tables below.

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One might argue that - because of the fact that the decision tables are semantically equivalent - it does not matter if you model the first or second table. However, there are two differences that are worth addressing and should be taken into account when designing decision tables:

1. If the party that uses this decision views its customers mostly with regards their gender, the first table is preferred. If they view their customers in age categories, the second is preferred.
2. In general the legibility of a decision table improves when the conditions are declared with the number of condition alternatives increasing from top to bottom. So even if the first argument of gender and age categories does not apply, there is a theoretical preference for the first table. This is illustrated below.

Decision table or data rule?

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