Measured SMV or typed SMV: the difference that decides your costing
Two factories quote the same polo shirt. One prices it from an SMV of 12.4 minutes that an industrial engineer measured on the line last month. The other prices it from an SMV of 11.0 that someone typed into a spreadsheet three seasons ago because it looked about right. Both quotes look equally confident on paper. Only one of them is a number.
The difference between a measured SMV and a typed SMV is not precision for its own sake. It is the difference between knowing your cost and guessing it, and everything downstream inherits the guess.
What a measured SMV carries
A real standard minute value comes from work study: cycle observations on the actual operation, a performance rating on the operator observed, and allowances added explicitly for fatigue, delay, and contingency. Each of those steps leaves a record. When someone challenges the number, the answer is not a shrug; it is a date, a method, and a set of observations anyone can re-run.
That record is what we mean by provenance. A standard with provenance can be defended to a buyer, audited by a costing team, and revised when the method changes. A standard without it can only be believed or disbelieved.
Where the typed number leaks money
The typed SMV does its damage quietly, in three places.
Costing. Labor cost per piece is SMV times the minute rate divided by efficiency. Underestimate the SMV by ten percent and the quote absorbs the loss on every piece of every repeat order. Overestimate it and the quote loses orders it could have won.
Planning. Line capacity is calculated from the same number. A plan built on an optimistic SMV books more output than the line can earn, and the factory discovers the gap as overtime and air freight rather than as a planning correction.
Performance. Efficiency is earned minutes over attended minutes, and earned minutes are pieces times SMV. Judge a line against a wrong standard and you either flatter it or punish it, and either way the improvement effort aims at the wrong target.
Estimates are fine, as long as they say so
No factory measures every style before quoting. Estimates are a legitimate tool, especially at the sampling stage. The discipline that matters is labeling: an estimated SMV should say it is an estimate everywhere it appears, so a costing built on it is understood as provisional, and so the measurement debt is visible instead of forgotten.
The failure mode is not estimation. It is an estimate that quietly hardens into a standard because nobody recorded which numbers were which.
What to do about it
Start with your twenty highest-volume styles. Measure them properly, record the method and the date, and mark everything else in your standard library as estimated until it earns otherwise. Track one number as a management metric: the share of production minutes running on measured standards. When that share crosses eighty percent, your costing, your plans, and your efficiency reports start agreeing with each other, because for the first time they are reading the same truth.
A quotation is a promise about the future. Measured standards are what let you make it honestly.
Further reading: CM Costing from First Principles and Line Balancing and the Operation Bulletin.