Certified in Planning and Inventory Management (CPIM) — Advanced Study Guide

Certified in Planning and Inventory Management (CPIM) — Advanced Study Guide

Issuing body: ASCM (Association for Supply Chain Management, formerly APICS) Jurisdiction: Global Level: Professional Prerequisites: None — no eligibility requirements to sit the exam (ASCM policy as of 2026). Experience in planning/inventory/ERP is helpful but not required. Renewal: 75 professional-development maintenance points every 5 years; lapse → suspension, then expiration requiring a full re-exam (per ASCM maintenance handbook)

1. How the credential is earned

1. Buy the CPIM bundle / Learning System from ASCM (or an ASCM partner/instructor-led course). The current version is CPIM 9.0, effective for exams purchased on/after February 3, 2026 (8.0 exams sunset May 31, 2026).
2. Study ~100 hours. ASCM's own guidance: candidates who test within 3 months of completing preparation pass at much higher rates. Schedule the exam when you buy.
3. Sit one computer-based exam: 150 multiple-choice questions (130 scored + 20 unscored), 3.5 hours, scaled score 300 to pass on a 200–350 scale. Administered at Pearson VUE centers and via OnVue online proctoring.
4. Maintain: 75 points per 5-year cycle (continuing education, presentations, published work, service).

Exam strategy: 3.5 hours / 150 questions = 84 seconds per question. The exam is calculation-heavy in the inventory and scheduling modules — memorize the formulas cold (EOQ, ROP, safety stock, load, available-to-promise) so arithmetic never costs you lookup time. The strategic modules (1, 2, 9) are judgment questions: think like a planner balancing service vs. cost, not like a theorist.

2. Knowledge domains (CPIM 9.0 — nine modules, official ASCM list)

Module 1 — Supply Chains and Strategy

Planning exists to reconcile competitive priorities (cost, quality, delivery speed, delivery reliability, flexibility, innovation) with operational capability. No firm wins on all six; the exam tests whether you can spot the priority implied by a scenario (e.g., a firm competing on customization needs flexible capacity, not low unit cost). Know the supply-chain strategy archetypes: lean/efficient vs. agile/responsive (Fisher's functional vs. innovative products) — functional products with stable demand → efficient chain; innovative products with unpredictable demand → responsive chain. KPIs cascade from strategy: perfect order fulfillment, cash-to-cash cycle time, supply-chain cost as % of revenue.

Module 2 — Sales and Operations Planning (S&OP)

S&OP is the monthly cross-functional process that balances aggregate demand and supply over a 12–18 month horizon. The standard 5-step cadence: (1) data gathering, (2) demand planning, (3) supply/capacity planning, (4) pre-S&OP reconciliation, (5) executive S&OP decision. The output is one agreed operating plan — the exam's trap answers propose letting sales and operations keep separate plans. Decisions made here: production rates, inventory targets, backlog, workforce levels (hire/fire/overtime/subcontract). S&OP works in aggregate (product families, not SKUs) — detail belongs to the master schedule.

Module 3 — Demand: forecasting and management

Forecasting techniques and their derivations:

• Moving average: F_t = average of last n actual demands. Simple, lags trends.
• Exponential smoothing: Ft = F{t-1} + α(A{t-1} − F{t-1}). The α (0–1) controls responsiveness: high α chases noise, low α lags shifts. Derivation logic: it is a weighted average with geometrically declining weights on older data.
• Trend-adjusted (Holt): adds a trend component T; forecast = level + trend.
• Seasonal: multiplicative or additive seasonal indices.

Accuracy metrics: MAD = mean |A − F|; MSE penalizes large errors; MAPE = mean |A−F|/A (watch: undefined at zero demand); tracking signal = RSFE / MAD — if it drifts beyond ±4, the forecast model is biased and must be revised. That ±4 rule is an exam favorite.

Demand management beyond the statistical forecast: the master schedule consumes the forecast through actual orders; abnormal demand (one-time spikes) must be flagged so it doesn't corrupt the forecast.

Module 4 — Internal Supply: capacity, MRP, production planning

Capacity planning hierarchy: Resource Requirements Planning (long-range, S&OP level) → Rough-Cut Capacity Planning (master-schedule level, critical work centers) → Capacity Requirements Planning (MRP-generated, all work centers) → input/output control (execution).

MRP logic — the heart of the exam. Given a master production schedule, MRP explodes the bill of materials:

1. Gross requirements from parent planned order releases.
2. Netting: net requirements = gross − (on-hand + scheduled receipts).
3. Lot sizing: L4L (lot-for-lot: order exactly net need), FOQ (fixed order quantity — use EOQ), POQ (periodic order quantity: cover P periods of net need, P = EOQ / average demand), EOQ.
4. Offsetting by lead time to get planned order releases.
5. Explode to components.

EOQ derivation (derive, don't just memorize): Annual total cost TC = (D/Q)·S + (Q/2)·H, where D = annual demand, S = ordering/setup cost per order, Q = order quantity, H = holding cost per unit per year. dTC/dQ = −DS/Q² + H/2 = 0 → *Q = √(2DS/H)**. Assumptions — and the exam tests these: constant known demand, constant lead time, no stockouts allowed, instantaneous replenishment, constant costs. Break any assumption and EOQ misleads (e.g., quantity discounts → evaluate total cost at each price break).

Load vs. capacity: load = scheduled work (hours); capacity = available hours. Utilization = load/capacity. RCCP flags overloads at bottleneck work centers — the exam expects you to shift the master schedule or add capacity (overtime), not to pretend the overload will absorb itself.

Module 5 — External Supply

Supplier planning mirrors internal planning: lead-time variability is the enemy. Know: supplier selection criteria (quality, delivery, cost, capability, financial health), single vs. multiple sourcing trade-offs, lead-time components (administrative, manufacturing, transportation, inspection), and total cost of ownership vs. piece price. Supply risk management: dual sourcing, safety stock for supply variability, supplier scorecards.

Module 6 — Inventory: the quantitative core

Inventory functions: anticipation, hedge, lot-size, transportation/pipeline, decoupling, safety. ABC analysis: A items ≈ 80% of usage value / 20% of SKUs — tight control, frequent review; C items — simple systems (two-bin). Cycle counting replaces wall-to-wall physical inventory; count A items most frequently.

Reorder point: ROP = d·L + SS, where d = average demand per period, L = lead time in periods, SS = safety stock.

Safety stock derivation: demand during lead time has standard deviation σ_dLT. For independent periods, σ_dLT = σ_d·√L (variances add, so standard deviations add in quadrature — the √L is the exam's favorite derivation). For a target service level with z-score z: SS = z·σ_d·√L. Example: 95% service → z = 1.65. This assumes normally distributed demand and independent periods — lumpy/intermittent demand breaks it.

Order quantity vs. order interval: fixed-quantity (Q-system: ROP triggers an order) vs. fixed-interval (P-system: order up to target at each review; needs more safety stock to cover review + lead time).

Inventory accuracy = (count matches / items counted); world-class ≥ 95–99%. Without accuracy, MRP generates garbage — "garbage in, gospel out" is the veteran's warning.

Module 7 — Detailed schedules

Scheduling: forward scheduling (start at due date minus lead times — shows earliest completion) vs. backward scheduling (start from due date, schedule operations in reverse — shows latest start; flags lateness). Dispatching rules: SPT (shortest processing time — minimizes mean flow time), EDD (earliest due date — minimizes maximum lateness), critical ratio = (due date − today) / remaining processing time — schedule lowest CR first; CR < 1 means the job is already late. Theory of Constraints: schedule the bottleneck (drum), protect it with buffers (buffer), subordinate everything else (rope) — DBR.

Available-to-promise (ATP): uncommitted inventory available for new customer orders = on-hand + scheduled receipts − committed orders. Capable-to-promise adds capacity checks.

Module 8 — Distribution

DRP (Distribution Requirements Planning) is MRP logic applied downstream: gross requirements come from forecasts/customer orders at each warehouse; netting, lot-sizing, and lead-time offsetting produce planned shipments. Know: distribution network structures (direct ship vs. warehousing vs. cross-dock), transportation modes (cost/service trade-off: air fastest/most expensive → ocean slowest/cheapest for freight), and the square-root law: consolidating n identical warehouses into 1 cuts safety stock by roughly √n — the quantitative argument for network consolidation.

Module 9 — Quality, continuous improvement, technology

Lean tools (waste elimination, pull, takt — see the Lean Certification guide), Six Sigma basics (DMAIC, variation reduction), and the technology layer: ERP as the system of record, planning data integrity (BOM accuracy, routing accuracy, inventory accuracy — the exam hammers that bad data kills planning systems), and emerging tech (AI/ML forecasting, digital twins).

3. Key equations

4. Worked examples

Example 1 — EOQ. D = 12,000 units/yr, S = $50/order, H = $3/unit/yr. Q* = √(2 × 12,000 × 50 / 3) = √400,000 = 632 units. Orders per year = 12,000/632 ≈ 19. Total cost = (12,000/632)(50) + (632/2)(3) = $949 + $949 = $1,898 (ordering and holding costs equal at optimum — a useful check). If a supplier offers 2% discount for Q ≥ 1,000: evaluate TC at Q=1,000 with discounted unit cost — discounts often beat EOQ.

Example 2 — Safety stock and ROP. d = 200 units/week, σ_d = 40, L = 3 weeks, 95% service (z = 1.65). σ_dLT = 40 × √3 = 69.3. SS = 1.65 × 69.3 = 114 units. ROP = 200 × 3 + 114 = 714 units. Raising service to 99% (z = 2.33) pushes SS to 161 — service gets expensive at the tail; that's the trade-off curve the exam probes.

Example 3 — MRP explosion. MPS: 100 units of A due week 6. BOM: 1 A needs 2 B's; B lead time 2 weeks; on-hand B = 60; no scheduled receipts. Gross B = 200 in week 6. Net = 200 − 60 = 140. L4L → planned order receipt 140 in week 6 → planned order release 140 in week 4. The exam's trap: forgetting to offset by lead time, or netting after offsetting (always net before offsetting).

Example 4 — Tracking signal. Forecast errors over 6 periods: +10, −15, −12, −8, −20, −5. RSFE = −50. MAD = (10+15+12+8+20+5)/6 = 11.67. TS = −50/11.67 = −4.29. Beyond −4 → forecast is biased high; revise the model.

Example 5 — Critical ratio dispatching. Today is day 10. Job X: due day 14, remaining time 6 days → CR = 4/6 = 0.67. Job Y: due day 18, remaining time 4 → CR = 8/4 = 2.0. Schedule X first (lowest CR); X is already late (CR < 1) — expedite or renegotiate.

5. Standards cross-reference

• APICS/ASCM body of knowledge is itself the standard for this exam — the Exam Content Manual defines the testable universe.
• ISO 9001 — planning and inventory controls (clause 8: operational planning, control of externally provided processes) are the QMS expression of CPIM disciplines.
• ISO 28000 (supply-chain security) — relevant to Module 5's supply-risk content.
• Incoterms 2020 (ICC) — Module 8 distribution: EXW/FOB/CIF/DAP define where cost and risk transfer.

6. Pitfalls and trap patterns

• EOQ assumption violations. Quantity discounts, shelf life, capacity constraints — if the scenario mentions any, EOQ alone is the wrong answer.
• Net before offset. MRP sequence errors are the most-tested procedural trap.
• S&OP aggregate vs. MPS detail. Answers that push SKU-level decisions into S&OP (or family-level decisions into the master schedule) are wrong.
• Service-level tail costs. Going from 95% → 99% service roughly doubles safety stock (z: 1.65 → 2.33) — the exam tests whether you see the nonlinearity.
• Forecast vs. plan. The forecast is an input; the plan (S&OP/MPS) is a management decision. Confusing the two fails scenario questions.
• Safety stock for the wrong variability. SS = z·σ·√L covers demand variability; if the scenario stresses lead-time variability, the correct response is supplier/lead-time management, not bigger SS.

7. Practice problems (answers at end)

1. D = 24,000/yr, S = $75, H = $4. Compute EOQ and orders per year.
2. d = 50/day, σ_d = 12, L = 5 days, target 97.5% service (z = 1.96). Find SS and ROP.
3. MPS needs 80 units of P in week 8. Each P uses 3 Q's. Q: on-hand 100, lead time 3 weeks, L4L. When is the planned order release for Q, and for how many?
4. Errors: +8, +6, −4, +10, +12, +9. Compute TS and interpret.
5. Today day 20. Job A: due day 25, remaining 3 days. Job B: due day 24, remaining 5 days. Which dispatches first by critical ratio?
6. A firm consolidates from 4 regional warehouses to 1. Roughly what happens to total safety stock, and what assumption does the square-root law need?

Answers: 1. Q* = √(2×24,000×75/4) = √900,000 = 949 units; ≈ 25.3 orders/yr. 2. σ_dLT = 12√5 = 26.8; SS = 1.96×26.8 = 52.6 → 53; ROP = 250 + 53 = 303. 3. Gross = 240; net = 140; release week 5 (8 − 3); 140 units. 4. RSFE = 41, MAD = 8.17, TS = 5.02 → biased low; revise upward. 5. CR_A = 5/3 = 1.67; CR_B = 4/5 = 0.8 → B first (and B is already late). 6. Falls to ~1/√4 = half; assumes identical demand variability and service levels across the warehouses.

Related credentials in this discipline

• CSCP (end-to-end supply chain) → certified-supply-chain-professional-cscp-study-guide.md
• Six Sigma Green/Black Belt → shared: ../shared/six-sigma-green-black-belt-study-guide.md
• PMP → shared: ../shared/pmp-study-guide.md

Original ETS reference writing, verified against public sources on 2026-09-30. Thin sourcing is flagged inline. Not legal advice — confirm current editions with the issuing body.