Focused Operations Management

Chapter 10. Evils of Long Response Times

Long response times for service, for production, and for development processes are a major concern in today's management world. In this chapter, we examine the relationship between response time and the amount of work in process (WIP), so that we may find ways to shorten these times.

Types of Inventories

The management of physical inventories (hardware, components, materials, documents, or files) and nonphysical and human inventories (pieces of software, business information to be processed, patients in the hospital or waiting for tests, or customers waiting in a bank) plays an important role in the management of business systems, operational systems, health care systems, and not‐for‐profit systems. Three types of inventories are shown in Figure 10-1 .

Raw materials (RM): Items that have not yet been handled: materials, components, information, or tasks before they enter the system to be processed.

Figure 10.1.  Figure 10-1: Types of inventories

Work in process (WIP): Items in process: intermediate products or tasks that have entered the system for processing. The processing on these items has not yet been completed.

Examples of work in process (WIP):

• Software and hardware that are still in development

• Items on an assembly line

• Purchase orders in the negotiating process or in the approval stage

• Receipts handled in the accounting department

• Business information ...