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Qwestrum Engineering360 · Industrial & Production · Supply Chain Management

Demand Planning

Demand planning creates a reliable future demand view for purchasing, production, and logistics.
Exam tip: keep SI units consistent end-to-end, write the governing relation symbolically before substituting, and sanity-check magnitude and sign.

Key formulas & points

Skim these first — then read the full notes below.

  • S&OP aligns demand and supply monthly
  • Collaborative planning CPFR with partners
  • Promotional lift separate from baseline

Topic details

Introduction

Demand planning sits at the center of S&OP process design. Chase highlights cross-functional consensus as essential to prevent functional silos and bullwhip.

Key relations & formulas

Formulas (Indian textbook notation)

  • forecastaccuracyMAPE=(1n)Σ∣A−F∣/A×100forecast accuracy MAPE = (\frac{1}{n})Σ|A-F|/A\times 100%

Formulas (Indian textbook notation)

  • bias=Σ(F−A)nbias = Σ\frac{(F-A)}{n}

Formulas (Indian textbook notation)

  • consensusforecastblendssales,marketing,opsconsensus forecast blends sales, marketing, ops

Notation and sign conventions

Relation 1 —
forecastaccuracyMAPE=forecast accuracy MAPE =

Formulas (Indian textbook notation)

  • forecastaccuracyMAPE=(1n)Σ∣A−F∣/A×100forecast accuracy MAPE = (\frac{1}{n})Σ|A-F|/A\times 100%
Write this relation with symbols exactly as in Sunil Chopra Scm — Standard reference before substituting numbers. Examiners award partial marks for a correct setup even when arithmetic slips.
Relation 2 —
bias=Σbias = Σ

Formulas (Indian textbook notation)

  • bias=Σ(F−A)nbias = Σ\frac{(F-A)}{n}
Write this relation with symbols exactly as in Sunil Chopra Scm — Standard reference before substituting numbers. Examiners award partial marks for a correct setup even when arithmetic slips.
Relation 3 —
consensusforecastblendssales,marketing,opsconsensus forecast blends sales, marketing, ops

Formulas (Indian textbook notation)

  • consensusforecastblendssales,marketing,opsconsensus forecast blends sales, marketing, ops
Write this relation with symbols exactly as in Sunil Chopra Scm — Standard reference before substituting numbers. Examiners award partial marks for a correct setup even when arithmetic slips.

Concept in depth

Analysts combine statistical baseline, market intelligence, and promotional inputs into a consensus plan. Accuracy and bias metrics are reviewed monthly, and exceptions are escalated. Buffa-style management interpretation should include capacity implications of forecast errors.

Assumptions and validity limits

State assumptions explicitly before using any relation for demand planning — steady state, uniform properties, linear elastic material, ideal gas, incompressible flow, etc., as applicable.
Wrong assumptions invalidate the entire solution even when the formula is correct. In Supply Chain viva and GATE descriptive questions, listing valid assumptions often earns separate marks.

Step-by-step problem approach

1. Read the question and list given data with SI units (common in Supply Chain papers).
2. Draw a neat labelled diagram where applicable — examiners in Indian universities award diagram marks even when arithmetic slips.
3. Identify which relation from this topic applies to demand planning.
4. Use equation 1:
forecastaccuracyMAPE=forecast accuracy MAPE =
.
5. Use equation 2:
bias=Σbias = Σ
.
6. Substitute values, compute, and verify units and sign (direction).
7. State conclusion in one line — e.g. safe/unsafe, stable/unstable, feasible/infeasible.

Applications & exam relevance

Demand Planning appears in FMCG and manufacturing. In Indian industrial curricula this topic is tested because it connects theory to procurement, logistics, and networks.
GATE and semester exams often combine demand planning with earlier units — revise prerequisites before attempting mixed problems.
Industry interview panels sometimes ask: "Where did you use demand planning?" — answer with a lab, mini-project, or plant visit example if possible.

Common mistakes in exams

A common issue is reporting low MAPE but ignoring large positive/negative bias. Students also mix percentage and absolute error units in the same calculation.

Quick revision checklist

Before attempting demand planning problems, confirm you can:
1. S&OP aligns demand and supply monthly
2. Collaborative planning CPFR with partners
3. Promotional lift separate from baseline
Revise the solved examples in Sunil Chopra Scm — Standard reference and one previous-year GATE or university paper for this unit.

Worked examples

Try the problem first — open the solution when you are ready to check.

MAPE from three periods

Problem

Actual demand: 100, 120, 80. Forecast: 90, 110, 100. Compute MAPE.

Solution

APE values: 10/100=10%, 10/120=8.33%, 20/80=25%. MAPE=(10+8.33+25)/3=14.44% approximately.

Conceptual check — Demand Planning

Problem

In a Supply Chain semester or GATE paper you are asked: "State the main assumption, the governing relation, and one practical consequence of demand planning." What should a complete answer include?

📖 Standard books (India)

  • Sunil Chopra Scm — Standard reference

    Read: Syllabus unit

    Referenced in Indian B.Tech syllabus

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