Operations Management: Core Formulas and Principles

Posted on Mar 6, 2026 in Business Administration and Innovation Management

Core Formulas

Control Limits:
UCL = μ + 3σ
LCL = μ − 3σ

1–10–100 Rule: Early detection saves exponential costs.

Cost of Quality = POC + PONC

  • POC: Prevention + Appraisal
  • PONC: Internal failure + External failure

TQM Principles

Customer Focus

TQM places customer satisfaction at the center of all activities. Organizations must understand the Voice of the Customer (VOC) and align processes to meet Critical to Quality (CTQ) requirements.

Process Management

Quality problems arise from faulty processes, not people. Improving process flow reduces variation and ensures consistency.

Continuous Improvement (Kaizen)

Small, incremental improvements over time lead to long-term excellence. It follows the PDCA cycle.

Leadership Commitment

Top management must set a quality vision, allocate resources, and build a quality culture. Without leadership, TQM fails.

Scientific Tools & Techniques

Data-based decision-making using QC tools promotes management by facts rather than assumptions.

Six Sigma Roles

  • Champion: Senior executive sponsor.
  • Black Belt: Project leader, expert in tools.
  • Green Belt: Team member executing projects.
  • Master Black Belt: Trainer and consultant.

Deming PDCA Cycle

  • Plan: Identify problem and solution.
  • Do: Implement on a small scale.
  • Check: Compare results with target.
  • Act: Standardize or modify.

The cycle repeats for continuous improvement.

Quality Gurus

  • Deming: 14 Points, build quality into the process, continuous improvement.
  • Juran: Fitness for use, emphasized Cost of Quality.
  • Crosby: Zero Defects, “Quality is Free,” doing it right the first time saves money.
  • Ishikawa: Fishbone diagram, quality circles.
  • Taguchi: Robust design, minimize variation from target value.

Exam Tip: Mention at least 2 gurus with 1 idea each.

Cost of Quality

  • Prevention Costs: Training, quality planning, process control.
  • Appraisal Costs: Inspection, testing, audits.
  • Internal Failure Costs: Scrap, rework, downtime.
  • External Failure Costs: Warranty, complaints, returns, lost sales.

Important Insight: As quality improves, failure costs decrease drastically. High quality leads to lower total cost.

Seven QC Tools

  1. Check Sheet: Data collection.
  2. Histogram: Frequency distribution.
  3. Pareto Chart: 80/20 principle.
  4. Fishbone Diagram: Root cause analysis.
  5. Scatter Plot: Relationship between variables.
  6. Control Chart: Process stability monitoring.
  7. Flow Chart: Process mapping.

These tools are simple, shop-floor oriented, and support PDCA.

Six Sigma Concept

Six Sigma focuses on reducing variation and shifting the process mean to the target. Variation is the enemy.

  • Reduce defects
  • Improve process capability
  • Achieve world-class quality

6σ = 3.4 defects per million opportunities.

Precision vs. Accuracy:
Precise but not accurate: Consistent but off target.
Accurate but not precise: On average correct but variable.
Best: Accurate + Precise.

DMAIC Methodology

  • Define: Identify problem, project scope, VOC, CTQ.
  • Measure: Collect data, calculate baseline DPMO.
  • Analyze: Identify root causes using statistical tools.
  • Improve: Develop and test solutions.
  • Control: Maintain gains using control charts and SOPs.

DMAIC is closed-loop and fact-based.

Operations and Project Management Q&A

Q1a: How to manage service level with safety stock?
Maintain target cycle service level (CSL) by holding safety stock (SS) where SS = z × σL. Reducing lead time directly reduces safety stock and total inventory cost.

Q1b: Service-level for ABC and VED categories?
Classify by ABC (usage value) and VED (criticality). A-Vital items get the highest CSL (97–99%) with continuous review; C-Desirable items get lower CSL (85–90%) with periodic review.

Q1c: Iron Triangle Concept?
Scope, Time, and Cost are interdependent. Managing a project requires optimizing tradeoffs among these three while protecting quality.

Q1d: APP Strategy: Chase or Level?
Chase strategy matches demand (minimal inventory, high hiring/firing costs). Level strategy keeps production constant (stable workforce, high inventory holding costs). Choose based on total cost analysis.

Q1e: WBS Padding?
Compounding 15% margins over five layers results in a total duration factor of ~2.01, meaning the final time is 201% of the original estimate.

Q1f: CPM vs. PERT?
CPM uses deterministic time estimates for repetitive tasks. PERT uses probabilistic estimates (a, m, b) for uncertain projects.

Strategic Operations

Q3v: Order Winners and Qualifiers?
An order qualifier is the minimum requirement to enter a market (e.g., safety standards). An order winner is the factor that differentiates the product and wins the customer (e.g., price, design).

Q2.1: MRP and Purchase Orders?
MRP uses the Master Production Schedule (MPS) and Bill of Materials (BOM) to calculate net requirements, which are then offset by lead time to generate planned order releases.