Case 01
Showing twelve unavailable observations instead of extending their last known value
In June 2024 we examined 360 observations displayed in a fleet-management view. Two hundred and eighty-eight had a current source within the agreed reporting conditions. Seventy-two were stale, although their presentation made them look as usable as the current values. The underlying assets were not necessarily unavailable. What we lacked was a dependable current observation through the reporting route. That difference was easy to lose in a portfolio discussion where a complete screen appeared to offer a complete account.
The dashboard sponsor favoured carrying the last known value until a replacement arrived, arguing that blank tiles would reduce confidence in the new view. I disagreed with presenting continuity of display as continuity of knowledge. Operations leader Chiharu Sumeraki helped define the status a reader needed, while my team retained the source time and the arrival time and made an unavailable condition explicit. We agreed a six-week programme costing JPY140 million to repair the feeds and the interpretation around them.
Sixty of the seventy-two stale observations acquired dependable current feeds within that work. Twelve did not and remained clearly marked unavailable, with owners for the remaining investigation. The final account therefore contained 348 current observations and twelve declared gaps. We did not substitute an assumed value merely to reach a complete-looking total. Nor did we report the twelve gaps as twelve failed assets. The programme concerned an enterprise reporting view; an operating assessment required the appropriate evidence from the site.
The price of my decision was a less reassuring presentation during the repair period and a continuing exception list afterwards. I considered that preferable to letting colleagues act on a certainty the system had not earned. We explained the distinction to the executives using the screen and retained the unresolved group in later reviews. The useful result was that a reader could see the boundary of the account, with a practical route to improve it, rather than mistake an old observation for a new fact about the fleet.
I would specify the treatment of unavailable observations before approving the dashboard, so readers and engineers agree what an empty or stale value means from the outset.