Direct-Cost Variances

Overview

• What you’ll learn: How to compute and interpret price and efficiency variances for direct materials and direct labor, the causes of each variance, and how managers use variance analysis to improve operations.
• Prerequisites: Lesson 4 — Flexible Budgets
• Estimated reading time: 17 minutes

Introduction

The Grand Historian records: When the general receives reports from the front, two questions dominate: Did we pay too much for our supplies? Did we use them wisely? These are the twin pillars of direct-cost variance analysis — price variances (what we paid vs. what we should have paid) and efficiency variances (how much we used vs. how much we should have used).

Horngren (Chapter 7) presents a systematic framework for decomposing the flexible-budget variance for direct costs into its price and efficiency components. This is forensic accounting at the operational level — diagnosing where value was created or destroyed on the factory floor.

The General Model

For any direct cost, the flexible-budget variance splits into two:

Price Variance = (Actual Price − Standard Price) × Actual Quantity

Efficiency Variance = (Actual Quantity − Standard Quantity Allowed) × Standard Price

Direct Materials Variances

Materials Price Variance (MPV)

MPV = (AP − SP) × AQ purchased

A favorable MPV means we paid less per unit than standard. Possible causes:

• Bulk purchasing discounts negotiated by a skilled procurement officer
• Lower-quality materials purchased (beware — this may cause unfavorable efficiency variances downstream)
• Market price decreases
• Favorable exchange rates for imported materials

Materials Efficiency (Quantity) Variance (MEV)

MEV = (AQ used − SQ allowed) × SP

A favorable MEV means we used less material than standard. Possible causes:

• Better-trained workers producing less scrap
• Higher-quality materials requiring less rework
• Improved production processes or machinery
• Favorable product mix with less material-intensive items

Direct Labor Variances

Labor Rate Variance (LRV)

LRV = (Actual Rate − Standard Rate) × Actual Hours

Causes of unfavorable rate variances include: using higher-skilled (and higher-paid) workers than planned, overtime premiums, or union-negotiated wage increases.

Labor Efficiency Variance (LEV)

LEV = (Actual Hours − Standard Hours Allowed) × Standard Rate

Causes of unfavorable efficiency variances include: poorly trained workers, equipment breakdowns, poor-quality materials requiring rework, and production scheduling inefficiencies.

Interdependencies Between Variances

太史公曰：The clever general who buys cheap swords saves on procurement but loses soldiers in battle. Variances do not exist in isolation. A favorable materials price variance from buying cheap inputs may cause unfavorable efficiency variances from higher waste. A favorable labor rate variance from using junior workers may cause unfavorable labor efficiency from slower production.

The wise manager examines variances as a system, not in isolation. The purchasing department’s “savings” may be the production department’s “waste” in disguise.

When to Investigate Variances

Not all variances warrant investigation. Management by exception focuses attention on significant deviations:

• Absolute threshold: Investigate if variance exceeds $X (e.g., $5,000)
• Percentage threshold: Investigate if variance exceeds X% of standard (e.g., 5%)
• Statistical control charts: Investigate if variance falls outside control limits
• Pattern analysis: Small but persistent variances may signal systematic problems

Key Takeaways

• Direct-cost variances decompose into price (rate) and efficiency (quantity) components.
• Price variance = (AP − SP) × AQ; Efficiency variance = (AQ − SQ) × SP.
• Variances are interdependent — a favorable price variance may cause unfavorable efficiency.
• Management by exception focuses investigation on material deviations.
• Root cause analysis, not blame assignment, is the purpose of variance analysis.

What’s Next

In Lesson 6, we ascend from the direct costs on the factory floor to the mists of variable overhead variances.