Definition
The sheet used on the floor to record how long each of an operator's steps takes and the full work sequence; normally 7 to 10 observations are taken and the shortest observable time for each step becomes that step's standard.
In detail
Taking the shortest rather than the average is the rule most often broken: the shortest value shows what the step can do when nothing goes wrong, while an average writes the abnormalities into the standard. Observation must be recorded step by step on the floor, not as a total cycle time — a total hides which step is varying. It feeds the other four standard work forms and provides the baseline for before-and-after comparison; reasons for abnormalities and waiting should be noted at the same time, because those are the improvement leads. How the cycle difference is redistributed follows one of two bases, and once chosen it must be applied consistently.
Example in practice
The team observes a station ten times; the shortest values of the six steps total 38 seconds against an actual average of 52. The 14 second gap sits almost entirely in waiting at the material pick step, which becomes the first topic of the kaizen week.