Separating waiting time from labour inefficiency
Efficiency variances often hide misclassified waiting hours. Supervisors usually know; the cost sheet does not.
When a line waits on material or a quality hold, some plants still book the hours to the productive cost centre. The efficiency variance then looks like a training or pacing problem. Supervisors describe the wait in one sentence; the cost sheet never hears it.
A simple bridge we build
Start with clocked hours by work centre. Split out overtime and temporary labour at rate. Then interview supervisors about downtime causes for the same days as the largest efficiency spikes. Match their notes to any downtime log that exists — even a whiteboard photo helps.
Language for the board
“Efficiency variance of X driven by Y hours of material wait on lines 2 and 3 during the resin shortage week” is a sentence operations and finance can both defend. “Labour productivity declined 7%” is not.
When HR pushes back
Reclassifying waiting time can touch incentive schemes. We document the evidence and leave policy changes to the client. Our job is a clean variance bridge, not a new bonus formula.
Commission a labour variance check if your efficiency line keeps surprising the board.