Even swaps

Use when

• A weighted matrix has failed to separate the leaders.
• You distrust arbitrary weights but can judge concrete trades.
• Criteria are in different units and forcing them onto one scale feels false.

Do not use when

• There are more than about five options — the swapping becomes long.
• You cannot state a trade in real units, which makes each swap a guess.

Inputs required

• A consequences table in natural units
• Willingness to state what a difference is worth

Procedure

1. 01

   Build the table

   Options down the side, criteria across, cells in natural units: pounds, minutes, square metres. No scores.

2. 02

   Delete dominated options

   Any option worse than another on every criterion goes, with no trade required.

3. 03

   Pick a criterion to eliminate

   Choose one where the options are close, since a small difference is easier to price honestly.

4. 04

   Make the swap

   Ask: what change on criterion B would exactly compensate for this difference on criterion A? Apply that change to the cell. You have now moved value between columns without changing the option’s overall worth.

5. 05

   Delete the equal column

   Once all options are equal on a criterion, that criterion cannot affect the choice. Remove it. The table shrinks by one column.

6. 06

   Repeat until one remains

   Each round removes a column or an option. The process terminates, and it terminates on a comparison you made explicitly rather than on a weight you guessed.