Summary of process analysis using activity categories based on the Lean/Six Sigma types of process waste, Toyota production system, and value stream analysis frameworks
| Process analysis framework | Activity type | General referrals | Dermatology referrals | ||||
| Steps | Time | Cost | Steps | Time | Cost | ||
| Value stream analysis | Value-add | 9 (21%) | 23% | 45% | 5 (21%) | 33% | 55% |
| Value-enabling | 23 (53%) | 55% | 33% | 15 (63%) | 51% | 26% | |
| NVA | 11 (26%) | 23% | 22% | 4 (17%) | 16% | 19% | |
| Toyota production system/perfect process analysis | Inspection/verification | 1 (2%) | 5% | 1% | 1 (4%) | 4% | 1% |
| Data entry/storage | 12 (28%) | 19% | 14% | 8 (33%) | 24% | 20% | |
| Data querying | 7 (16%) | 27% | 14% | 5 (21%) | 22% | 5% | |
| Reminders | 3 (7%) | 4% | 4% | 1 (4%) | 2% | 0% | |
| Lean/Six Sigma process waste categories | Scrap and rework | 6 (14%) | 7% | 6% | 2 (8%) | 4% | 1% |
| Travel/transportation | 2 (5%) | 8% | 9% | 1 (4%) | 4% | 8% | |
| Delay/waiting | 3 (7%) | 9% | 7% | 1 (4%) | 8% | 10% | |
Items listed under Toyota production system categories represent value-enabling items; those under Lean/Six Sigma process waste categories represent NVA activities. Time-driven activity-based costs used an average hourly wage of $103 for primary care providers, $19 for medical assistants and clinical administrative assistants, $120 for specialists and $151 for dermatology specialists.10 11
NVA, non-value add.