Advanced variances and reconciliation - Mix and yield; plann...

Learning Outcomes

After studying this article, you will be able to calculate and interpret material mix and yield variances for processes involving multiple materials, distinguish between planning and operational variances, and explain how advanced variance analysis leads to more accurate assessment of management performance. You will also learn to reconcile these variances and discuss their application in fair control and motivational systems.

ACCA Performance Management (PM) Syllabus

For ACCA Performance Management (PM), you are required to understand how advanced variance analysis supports business control and performance assessment. This article targets the following key areas for your revision:

• Calculate, explain and interpret material mix and yield variances
• Reconcile usage variance into mix and yield variances
• Discuss the implications of changing material mix, including quality and cost consequences
• Calculate, explain and interpret planning and operational variances for materials and labour
• Analyse variances for performance evaluation and management responsibility
• Use advanced variance analysis to support fair management appraisal and motivation

Test Your Knowledge

Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, remember to look more closely at that area during your revision.

1. In what types of production settings are material mix and yield variances relevant, and why might a favourable mix variance lead to an adverse yield variance?
2. What is the difference between a planning variance and an operational variance, and who should be held responsible for each?
3. How can splitting variances into planning and operational components improve management performance evaluation?
4. What is the relationship between material usage variance and mix and yield variances?

Introduction

Basic variance analysis involves comparing actual results to standard or budgeted expectations. At the advanced level, you need to split material variances into mix and yield, and also separate total variances into planning and operational components. These skills are essential to evaluate efficiency, controllability, and fair performance in a modern business context where material proportions and external factors are frequently changing.

Key Term: material mix variance
The variance that measures the effect on total cost of using input materials in different proportions to those specified in the standard mix, valued at standard prices.

Key Term: material yield variance
The variance that captures the efficiency of converting total material inputs into finished outputs, showing the difference between actual and standard output for the quantity of inputs used, valued at standard cost per unit.

Key Term: planning variance
The part of a variance that arises due to changes in standards or budgets for reasons outside the control of a manager, such as market price jumps or new specifications.

Key Term: operational variance
The portion of a variance that is due to the manager’s actual performance against a revised, realistic standard reflecting the business conditions at the time.

Understanding Material Mix and Yield Variances

Material mix and yield variances are used when:

• A process or product is produced from more than one material type;
• The proportions (mix) of those materials can vary in practice and affect costs or output;
• Management wishes to identify whether using different material proportions or total input quantities has impacted cost or process efficiency.

Material Mix Variance

A mix variance isolates the effect on cost of using materials in different proportions compared to the standard recipe, assuming total material quantity is constant. Use standard prices in all mix calculations.

Steps to Calculate Material Mix Variance

1. Add up the total actual quantity (kg/litres) of all materials used.
2. Calculate how much of each material should have been used, in standard proportions, for that actual total input.
3. For each material, calculate: (Standard quantity for actual total input − Actual quantity used) × Standard price.
4. Total the variances for all materials. The sum will be zero in physical units (since any excess of one material is offset by less of another), but not in cost.

Material Yield Variance

The yield variance measures how efficient the process was at converting total input into output, irrespective of the proportions of materials. If actual output is less than the expected output for the actual input, yield variance is adverse.

Steps to Calculate Material Yield Variance

1. Determine the standard output (yield) expected from the actual total input (using the standard loss % or input/output ratio).
2. Subtract actual output from standard output to get the difference in units (positive if output is higher than expected, negative if lower).
3. Multiply the difference by the standard material cost per unit of output.

Relationship:
Material usage variance = Mix variance + Yield variance

Key Term: material usage variance
The variance that shows the cost impact of using more or less total material compared to the standard allowed for the actual output.

Worked Example 1.1

A process requires a standard input of 600 kg of Material A at $2/kg and 400 kg of Material B at $4/kg, to produce 900 units of finished product (expecting some input loss). During the month, actual input was 660 kg of A and 320 kg of B, and actual output was 940 units.

Required:
Calculate the total material mix and yield variances.

Answer:

Total input: 660 + 320 = 980 kg
Standard mix for 980 kg:

• Material A: 60% × 980 = 588 kg
• Material B: 40% × 980 = 392 kg

Mix variance:
Material A: (588 − 660) × $2 = (−72) × $2 = $144 A
Material B: (392 − 320) × $4 = (72) × $4 = $288 F
Total mix variance = $288 F − $144 A = $144 Favourable

Expected yield:
Standard output per 1,000 kg input = 900 units, so per kg = 0.9 units
Expected output from 980 kg = 980 × 0.9 = 882 units
Yield variance in units = 940 − 882 = 58 units Favourable

Standard cost per unit of output = (600 × $2 + 400 × $4) / 900 = ($1,200 + $1,600) / 900 = $3.11
Yield variance = 58 × $3.11 = $180.38 Favourable

Interpreting Results

A favourable mix variance combined with a favourable yield suggests that cheaper or higher-quality materials were substituted or that the process was run efficiently. Beware: in some cases, using more of a low-quality material may give a favourable mix variance but reduce the yield or quality, leading to an offsetting, adverse yield variance.

Exam Warning

If mix and yield variances both move in opposite directions, always consider if the saving in one is offset by inefficiency or excess cost in the other. Candidates frequently lose marks by failing to reconcile the variances or by discussing them in isolation.

Planning vs Operational Variances

Variance analysis should only use a fair standard for assessment. If the standard was unrealistic (e.g. market price rose unexpectedly), it can lead to unjust criticism or reward. To resolve this, split each variance as follows:

• Planning variance: The impact of the revised standard (what should have been allowed if planning had been realistic), representing uncontrollable, external factors.
• Operational variance: The impact of actual results against the revised standard (the manager’s controllable performance).

Planning and Operational Variance Calculations

• Planning variance: (Original standard − Revised standard) × Actual quantity (price) or Actual output (quantity).
• Operational variance: (Revised standard − Actual) × Actual quantity (price) or Actual output (quantity).

Worked Example 1.2

A business set a standard price of $5/kg for Material Q. Unexpected supply shortages raise the price to $7/kg in the month. Actual usage is 2,000 kg at $7/kg.

Required:
Calculate the planning and operational price variances.

Answer:

Planning price variance:
($5 − $7) × 2,000 kg = (−2) × 2,000 = \4,000 Adverse

Operational price variance:
($7 − $7) × 2,000 kg = $0

The entire adverse price variance was due to uncontrollable market movement, not the manager’s performance.

Reconciliation and Responsibility

Splitting variances ensures only operational variances are used to judge performance, motivating managers to focus on factors within their control.

Worked Example 1.3

A standard labour time of 2 hours per unit was set. Due to a new legislation, the actual time per unit realistically should have been revised to 2.3 hours. 400 units were produced in 920 hours. The standard wage rate is $11/hr.

Required:
Calculate the planning and operational labour efficiency variances.

Answer:

Original standard hours for 400 units = 2 × 400 = 800 hours
Revised (planning) standard hours = 2.3 × 400 = 920 hours
Actual hours used = 920

Planning efficiency variance = (800 − 920) × $11 = (−120) × $11 = $1,320 Adverse
Operational efficiency variance = (920 − 920) × $11 = 0

Revision Tip

Focus appraisal on operational variances, not planning variances, for fair performance management. When reviewing variances, always reconcile usage to mix plus yield.

Summary

Advanced variance analysis—splitting material usage into mix and yield variances, and separating planning and operational components—provides a clearer picture of what the business can control and what it cannot. Reconciling these variances gives a fairer measure for management appraisal, supports motivation, and helps target improvements more accurately.

Key Point Checklist

This article has covered the following key knowledge points:

• Calculate and interpret material mix and yield variances, and how they reconcile to usage variance
• Recognise the types of situations where mix and yield variances are necessary and meaningful
• Identify when planning and operational variances should be used and how to calculate them
• Evaluate performance fairly by splitting variances into controllable (operational) and uncontrollable (planning) elements
• Use advanced variance analysis to support performance improvement and motivation

Key Terms and Concepts

• material mix variance
• material yield variance
• material usage variance
• planning variance
• operational variance