TOC course · Lesson 6 of 6
Run a four-week constraint experiment
Complete the TOC cycle by making a prediction, changing the operating system, protecting necessary conditions, and deciding from observed flow.
The capstone hypothesis
This hypothesis is deliberately falsifiable. It predicts both improvement and a guardrail. It also predicts that execution may become the next constraint.
The four-week protocol
| When | Action | Evidence |
|---|---|---|
| Before Week 1 | Confirm system boundary, active RFC list, phase definitions, and ownership. | Baseline WIP, age, transition rate, delivered/invoiceable RFCs, SLA. |
| Twice weekly | Run a 45-minute clinic in age order. Every RFC leaves with a customer decision, proposal, plan-ready move, or explicit blocker/closure decision. | Blocked days by reason and transitions to plan-ready. |
| Continuously | Admit only complete decision packets; do not create clarification work without an owner and next decision date; protect execution only for plan-ready work. | Ready backlog, execution age, interruptions, SLA. |
| End of Week 2 | Check adherence; fix the experiment, not the hypothesis. | Was the intervention actually applied? |
| End of Week 4 | Compare observed signature with prediction and choose the next focusing step. | Throughput, leading measures, guardrails, new accumulation point. |
Use one scorecard, not a dashboard zoo
| Role | Measure | Decision it supports |
|---|---|---|
| Leading | Median age in clarification; plan-ready transitions; touch-time share by phase. | Is the limiting mechanism changing? |
| Outcome | Delivered and invoiceable RFCs; project throughput when classified. | Did system output improve? |
| Guardrail | Recurring-service SLA and incident/service-request age. | Did improvement damage a necessary condition? |
| Movement | WIP and age in execution, verification, invoicing, and collection; incident/SR capacity mix. | Where should identification restart? |
Interpret the result
Predicted improvement
Plan-ready and invoiceable flow rise; SLA holds. Continue until another point limits throughput.
Queue moves downstream
Clarification falls; execution or verification age rises. Return to Step 1 there.
No response, good adherence
The hypothesis is weakened. Re-examine blocker causes, system boundary, or another constraint.
No response, poor adherence
The experiment is inconclusive. Repair the operating rules before judging the hypothesis.
Throughput rises, SLA falls
The change violated a necessary condition. Redesign shared-capacity subordination.
Flow rises, cash does not
Expand the boundary: invoicing or collection may now constrain cash throughput.
Final retrieval check
Capstone submission
System and goal:
Constraint hypothesis:
Evidence supporting it:
Exploit decision:
Subordination rules:
Possible elevation:
Leading measure:
Outcome measure:
Guardrail:
Movement signal:
Disconfirming result:
Review date:
Primary reading
- Goldratt Research Labs: What is TOC? — review the complete Five Focusing Steps.
- IT-Premium Value Streams & Flow Constraints — compare this protocol with its measured diagnosis and four-week experiment.
- TOCICO — use the practitioner community to test implementation assumptions and learn from service cases.