Measuring plan reliability with percent plan complete
For the third Monday running, the weekly plan on the trailer whiteboard is wiped and rewritten. Every foreman says last week went well, yet the level 2 ceilings are two weeks behind. Nobody can say how many of last week's promises were kept.
Measure plan reliability weekly: the tasks on the weekly plan finished as promised, divided by all the tasks promised, is percent plan complete (PPC). For each miss, get one reason from the foreman who promised it and tally the reasons over several weeks; the most common is the first to remove. PPC shows whether the plan came true, not how hard people worked, and the Lean Construction Institute calls it a basic measure of how well the planning system is working. Its standard work puts a high-performing team's average at 75 to 90 per cent.
- Write each promise so anyone can check it: task, area and finish day. "Level 2 east corridor, board hung both sides, Thursday", not "drywall level 2".
- Freeze the list at the weekly meeting. Work added during the week is welcome but not counted.
- Count at the end of the week: finished as promised, or missed. The institute counts only tasks 100 per cent complete as planned, so 90 per cent done is a miss. PPC is finished ÷ promised × 100.
- Take each miss's reason from the person who promised it, from a short list agreed before the first count. The institute's list includes prerequisite work, design, inspections, labour, material, equipment, submittals and weather. Note the trade.
- Post both where the foremen meet: PPC week by week, and the reasons over the last four weeks.
- Remove the top reason at its source: ask why the task was promised when it could not be done, until you reach a planning step you can change. Readiness checks belong in the constraints log.
Common mistakes
- Counting a task 90 per cent done, or finished a day late, as kept.
- Adding work that did get done to the list afterwards.
- A PPC target for each trade, which teaches foremen to promise less.
- Accepting "other" as a reason.
Checklist
Friday's count
- The list as promised at the weekly meeting
- Each task finished as promised, or missed
- PPC: finished ÷ promised
- A reason for every miss, from whoever promised it
- Reasons tallied over four weeks
- One reason chosen to remove, with a name against it
Check your understanding
PPC has been 100 per cent for four weeks, but the look-ahead shows level 3 falling behind. What do you check?
