Ledger / Journal / What a sampling window is allowed to cover
What a sampling window is allowed to cover
The window is a promise about time. Broken promises show up as suspiciously smooth ink.
People like to start a window on a Monday after a shutdown, because the floor is tidy. They like to end it before a feast, because the book will be late. The chart then describes a polite fortnight that the year will not repeat.
A sampling window should name, in advance, the days that cannot honestly be included: the festival, the planned stop, the Friday the van has the log. It should also name the days that must be included even though they are ugly: the night the second oven is down, the shift that is always short one person.
I would rather a two-week window with a hole drawn on Friday than a “complete” fortnight that never saw Friday. In the log, an unread meter is written unread. In the chart, that day is a gap, not a guessed average.
If your calendar is a tangle, ask for a sampling plan before the audit. Arguing the window on paper is cheaper than discovering, in a briefing, that nobody believes the fortnight.