Baseline or last-approved programme — which should you measure against?

Two questions, and they are not the same question

The baseline is the programme agreed at sanction. Measured against it, you are asking: how far is this from what we were promised? That number is what the contract is measured on, what the board asks about, and — on most projects — what grows.

The last-approved programme is last month’s submission. Measured against it, you are asking: what moved, and why? That number is actionable precisely because it is small. A three-day slip on one milestone has a cause somebody can still name.

Why a contractor would rather you only used one

Read only against last month, and drift disappears into the rounding. Twelve modest, well-explained monthly slips are a year — but no single month ever looked alarming, and each one arrived with a reasonable explanation attached.

Read only against the baseline, and you get the opposite failure. The variance is so large and so old that nobody can attribute it to anything, every review becomes a conversation about a number, and the actual causes — which happened in specific months, for specific reasons — are long past being findable.

Neither lens is dishonest on its own. Both are incomplete, and the incompleteness runs in a convenient direction.

The pair is the instrument

So every submission is read twice. Against the baseline, for the position. Against last month, for the movement. The two together are what let you say: we are 47 days behind sanction, 6 of them arrived this month, and here is what caused those 6.

That sentence is the entire job. One lens gives you the 47 and no explanation. The other gives you the 6 and no context.