Bad actors and the jack-knife diagram
A “bad actor” is a repeat offender: an asset or a failure mode that consumes a disproportionate share of downtime, cost, or attention. Finding the list is not the same as fixing the item, but it is how you decide where the next RCA or RCM hour should go.
A straightforward ranking uses event count, downtime hours, and cost over a stated period. A jack-knife style plot is one way to show that ranking: items are ordered, and a cumulative curve makes it obvious whether a handful of names dominate the total. In many plants they will. That is a description of your history, not a law that the split is 80/20.
Two cautions. First, a short observation window can make a one-off event look like a chronic problem, or hide a slow one. Second, cost has to be estimated consistently — see downtime cost per hour — or the ranking will just follow whichever event had a dramatic invoice attached. The Bad Actor Analysis Toolkit is built for this ranking; the next investigation is often an RCFA.