Lead-time distribution and service level expectation — spares kanban
Lead-time histogram of 60 completed replenishment orders with the 50th, 85th and 95th percentile lines, the figure a flow or kanban team uses to quote a service level expectation instead of an average.
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title: Lead time distribution - CNC spares kanban, 12 weeks
subtitle: 60 completed replenishment orders, card posted to part on the shelf
x: Lead time (days)
y: Orders completed
grid: y
legend: bottom
note: Nearest-rank percentiles: 50th 6 d, 85th 14 d, 95th 24 d, longest 38 d
note: Service level expectation quoted to the customer: 85 percent of orders within 14 days
note: Mean 8.47 d and throughput 5 orders per week give average WIP 6.0 by Little's law - the board limit is 6
note: The distribution is right-skewed, so the mean is not a commitment and an average lead time quoted as one will be missed about half the time
histogram "Completed orders" bins: 19
values: 1 1 1 2 2 2 2 2 3 3 3 3 3 3 4 4 4 4 4 4 4 5 5 5 5 5 5 6 6 6 6 6 7 7 7 7 8 8 8 8 9 9 9 10 10 11 11 12 12 13 14 15 16 18 19 21 24 27 31 38
line "50th percentile 6 d"
6 0
6 13
line "85th percentile 14 d - SLE"
14 0
14 13
line "95th percentile 24 d"
24 0
24 13