Supply Chain and Operations Management Glossary (W)

Wardrop’s Principle: A traffic equilibrium rule. Suppose commuters wish to travel from A to B. According to Wardrop’s principle, at a user equilibrium where users choose the paths, among all paths along which there is a positive A-to-B traffic, the travel time from A to B will be the same, whereas the travel time from A-to-B is at least as great along paths not carrying any A-to-B traffic. See also: Nash Equilibrium and Braess’s paradox.

Warehouse: A DC in which product may be carried for an extended period of time, such as product that either has seasonal production or seasonal demand. Some warehouses may be specifically designed to handle refrigerated goods, high value/security goods, flammable goods, or other hazardous materials.

Warsaw convention: An international treaty ratified by most countries between 1929 and 1934 that sets standards for air carrier liability. For example, it sets standards for the minimum $/lb that an air carrier is liable for loss of goods, as well as the length of time a shipper has to submit a claim for damaged goods.

Wave: In some warehouses, picking is done in batches called waves. A major motivation for waves is to gain economies of scale in picking. E.g., if only a few items are picked at a time, then manual pickers must do a lot of walking between picks of individual items. After one wave, one set of trucks are typically loaded.

WBS (Work Breakdown Structure): In project management, a hierarchal or tree-structured arrangement of the work to be done. At the highest level is the final deliverable. It is broken down into or described in terms of its components. These in turn or broken down, etc. Management of activities is frequently assigned in terms of the WBS, so being able to view the status of a project according to its WBS may be convenient for the individual manager.

WERC: Warehousing Education and Research Council. See

Winner’s curse: In auctions, the observation that the winner of an auction has a higher than average probability of having made an (optimistic)error in preparing his bid.

WIP (Work in Process): Inventory of partially completed product.

WMS (Warehouse Management System): A mainly software system for keeping track where product is stored in a warehouse, generating pick lists, and in general causing the proper outbound shipments to be constructed.

WTO: (World Trade Organization)

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