Final answer:
The production department is typically the first to investigate an unfavorable materials quantity variance to discover if production inefficiencies or waste occurred. If production is not at fault, other departments might be involved to pinpoint issues related to material quality, purchasing decisions, or handling.
Step-by-step explanation:
When it comes to identifying which department would normally begin an investigation regarding an unfavorable materials quantity variance, several departments could be involved. However, the primary responsibility typically falls on the production department. This department is directly involved with the usage of materials and will first assess if the variance is due to inefficiencies or wastage in their processes. If the production department concludes that the issue is not with the production processes, then other departments such as quality control, purchasing, engineering, or receiving may subsequently be involved to identify if the issue is related to the quality of materials, vendor selection, material specifications, or handling of materials upon receipt.