Five questions before you weight an index

Weights feel mathematical until someone realises a favourite metric just lost influence. Before the sticky notes come out, walk these five questions with the people who will live with the index.

1. Does this measure move first?

If it only confirms what last month’s P&L already said, it is lagging colour, not an index driver. Keep it nearby as a supporting chart if the room needs comfort — leave it out of the weight table.

2. Can it refresh on the stated cycle?

A beautiful weekly index that depends on a monthly extract will amber for the wrong reason. Either change the cycle or change the measure.

3. Who owns the definition in writing?

Verbal definitions drift. Name a person, not a department, and put the sentence beside the weight.

4. What breaks if we drop it?

If nothing in the Monday huddle changes when the measure is absent, it was decoration.

5. What is the change rule?

Indexes rot when anyone can tweak a weight after a bad week. Decide whether changes wait for the planning freeze, and write that rule before you draw the first panel.

Bring answers to these into discovery and the design days shrink. We still argue — just about the few drivers that earn a place on the spine.