Understanding the Audit Concern:

The internal auditor observed a significant decline in tire production and needs to assess whether worker inefficiency is the cause.

Worker inefficiency is typically measured in terms of productivity, which relates output (number of tires produced) to input (labor hours worked).

Why Option A is Correct?

Total tire production labor hours provide a direct measure of worker efficiency. By analyzing the number of tires produced per labor hour, the auditor can determine whether efficiency has declined.

If labor hours remained constant or increased while production declined, this indicates inefficiency.

This approach aligns with IIA Standard 1220 – Due Professional Care, which requires auditors to use appropriate analysis to support findings.

Additionally, per IIA Standard 2310 – Identifying Information, auditors must obtain sufficient and relevant data to support conclusions.

Why Other Options Are Incorrect?

Option B (Total tire production costs):

Total costs include factors beyond labor efficiency, such as raw material prices, machinery maintenance, and overhead. This does not directly measure worker productivity.

Option C (Plant production employee headcount average):

Employee headcount alone does not reflect efficiency; it does not account for hours worked or individual performance.

Option D (Production machinery utilization rates):

Machinery efficiency is important but does not directly measure worker inefficiency. A decline in machine utilization could be due to maintenance, material shortages, or other non-labor factors.

Labor hours per unit of production (tires produced per labor hour) is the best metric for evaluating worker efficiency.

IIA Standards 1220 and 2310 support data-driven, relevant information gathering for audit conclusions.

Final Justification:IIA References:

IPPF Standard 1220 – Due Professional Care

IPPF Standard 2310 – Identifying Information

Performance Standard 2320 – Analysis and Evaluation