Start with something familiar
A cook needs more than the guest forecast. The pantry, incoming groceries, and earlier promises all affect what must be prepared. A shop shortage does not mean fewer guests wanted dinner. A useful handoff preserves the attendance picture while exposing the practical gap and possible responses. It also records when the ingredients arrive: supplies that come after the meal cannot solve the earlier shortage simply because they appear in the weekly total.
Words to know: Backlog, Forecast consumption, Scenario.
Publish a demand contract
State product, location, unit, bucket dates, issue time, horizon, and scenario. Include baseline, approved adjustments, consumed orders, separate old backlog, and quality limitations. The demand owner describes expected customer wants; the supply owner evaluates feasible fulfillment. These are linked decisions with different responsibilities, not interchangeable versions of one number.
Fresh demand fifty-one plus backlog six gives fifty-seven obligations. Stock eighteen and on-time receipts ten leave twenty-nine to obtain. Quarantined or reserved stock is not usable. A receipt after the need date cannot offset an earlier requirement without accepting delay. Document timing and eligibility rather than relying on a period-total shortcut.
Expose the limiting capability
Supplier availability twenty-four, manufacturing thirty-two, and shipping thirty mean twenty-four additional usable units if they are sequential limits on the same flow and period. Do not add capacities. Against requirement twenty-nine, the gap is five. Do not reduce the demand forecast to hide that gap; retain a separate feasible fulfillment view.
Recovery may involve earlier supply, approved substitution, increased capacity, or customer rescheduling. Each option needs an owner, lead time, and effect on the gap. Deferring five units does not erase demand. Keep original due dates and revised promises so later service and backlog reports reflect what actually happened.
Handoff scenarios and checks
Fresh low/base/high demand forty-three,fifty-one,sixty-three gives net requirements twenty-one,twenty-nine,forty-one with the same backlog, stock, and receipt. Against twenty-four usable additional units, low has three headroom and base/high gaps five,seventeen. These cases let the supply team tie actions to observable demand triggers.
A separate production check for twenty-nine good units at expected yield 97% suggests thirty starts, with expected output 29.1, never a guarantee. Thirty starts at twelve minutes plus one thirty-minute changeover use 390 of 480 usable minutes, leaving ninety. This hypothetical calculation does not resolve the supplier constraint; assumptions must stay distinct.
- Define target
- Check evidence
- Calculate
- Challenge assumptions
- Record decision
Hand demand to supply with a complete bridge — worked case
All inputs below describe fictional Northstar bottles. Keep the stated units and timing when reproducing the calculation.
| Input | Units |
|---|---|
| Fresh demand | 51 |
| Backlog | 6 |
| Stock | 18 |
| On-time receipt | 10 |
| Supplier | 24 |
| Manufacturing | 32 |
| Shipping | 30 |
- 1. Net requirement = 51+6-18-10 = 29.
- 2. Common-flow limit = min(24,32,30) = 24.
- 3. Uncovered requirement = max(0,29-24) = 5.
Net requirement 29; limiting capability 24; gap five.
Assumptions
- Periods and quantities use the definitions stated in this example.
- Only explicitly supplied events or adjustments are included.
Where this can fail: The arithmetic checks the stated assumptions; it does not establish that uncertain future events will occur.
Build, test and explain a plan
Four-week fresh demand [51,54,55,58]; initial backlog six; initial stock eighteen; scheduled receipts [10,0,0,0]; additional good-unit limits [24,50,60,60]. No further manufacturing or shipping limits after week one. Carry unmet obligations as backlog and surplus stock; no cancellations or safety stock. All units are bottles unless stated otherwise. Use a spreadsheet or ruled paper. Eight hours includes construction, comparison, writing, and teach-back; this is a planning estimate, not an experimentally validated completion time.
Use paper or a spreadsheet. The estimates below include the study and worked example already on this page.
| Estimated hours | Activity |
|---|---|
| 0.5 | Study the lesson and write a data dictionary defining every field, time bucket, unit, and cutoff. Separate observed facts from assumptions. Identify two ways a colleague could misread the target and rewrite its definition to prevent those errors. |
| 0.5 | Reproduce the worked example independently, showing formulas and intermediate values. Compare against the answer and keep a correction log explaining each difference. Check one result a second way using a total, balance, or direct manual calculation. |
| 3 | Build a rolling ledger with fresh demand, incoming backlog, stock, receipts, additional supply, fulfillment, ending backlog, and ending stock. Attach a demand version sheet. Reconcile weekly and cumulative views. Keep inputs separate from formulas, label every origin and target, and add independent row and total checks. Produce an annotated chart with at least two observations tied to specific rows; include a brief explanation of why each check matters. |
| 2 | Compare five extra usable units in week one with no recovery. Separately run downside demand [43,46,47,50], high [63,66,67,70], and delay the ten-unit receipt from week one to week two. Preserve each variant separately. Create an output comparison table and explain which changed assumption caused each movement. Identify a scenario that affects timing differently from totals and state what the planner should do with that distinction. |
| 1 | Write a 400-word decision memo using your own numerical outputs. State the proposed action, evidence, two limitations, an owner for the next check, and a measurable condition that would change your recommendation. Attach the model so a reader can audit every cited value. |
| 1 | Prepare a five-minute teach-back using one worked row and one scenario comparison. Explain it aloud to a colleague or recording. Write three skeptical questions, answer them with evidence, and revise the memo or model where your explanation exposes an unsupported assumption. |
Your deliverables
- Auditable input and formula model with checks
- Scenario comparison and annotated chart
- Decision memo, correction log, and teach-back notes
Check your practice work
- Base obligations 224 and supply 222 leave final backlog two.
- Base ending backlog [5,9,4,2]; stock zero.
- Five extra week-one units yield backlog [0,4,0,0], stock [0,0,1,3].
- Downside backlog zero, stock [3,7,20,30]. High backlog [17,33,40,50].
- Delayed receipt gives backlog [15,9,4,2]: same final shortage, worse week-one service.
- ceil(29/0.97)=30 starts, expected 29.1 good. Load 30×12+30=390 minutes; headroom ninety.
Keep these three ideas
- Publish a versioned forecast, net requirement, constraint gap, and recovery choices.
- Keep original evidence distinct from modeled values and assumptions.
- A precise output remains conditional on definitions and timing.
Common mistakes
- Overwriting the original evidence after a revision.
- Reporting a number without its unit, period, cutoff, and assumptions.
Optional video study
Publish a versioned forecast, net requirement, constraint gap, and recovery choices.
- Publish a demand contract
- Expose the limiting capability
- Handoff scenarios and checks
One half of the module narration, with a distinct Northstar calculation and a bridge to the paired lesson.
Open the module media & quizPut this idea to use
Carry your assumptions into a practical tool, then compare your result with a short guide.
Open a related planning toolRead the related planning guidePractice with the planning gameThis saves a completion marker in this browser only. It does not verify time spent.