between January 1997 and January 2000, the percentage of commission-based trades being conducted online by Boston-based Fidelity Investments Institutional Services Company, Inc., jumped from 7 percent to 85 percent. Many online brokerages have discussed the possibility of turning down potential online accounts as a means of addressing such growth. See Meehan (2000).

14. This discussion of complexity borrows from the work of Perrow (1984) and Reason (1990).

15. However, as any commuter knows, just one small accident or other disturbance in normal traffic patterns can create significant delays on busy roadways.

16. See CSTB (1999a), especially Chapter 5, “Trustworthy Systems from Untrustworthy Components.”

17. Middleware is a layer of software that lies between the operating system and the application software. Different middleware solutions support different classes of applications; two distinct types support storage and communications. See Messerschmitt (2000).

18. A discussion of the fundamental problems in mobile and wireless communications can be found in CSTB (1997).

19. For example, a typical desktop computer contains an operating system and application software developed by many different companies. Although an automobile may also be composed of components from a number of suppliers, they tend to be fitted together into a test car before manufacture, and final assembly of each car takes place in a limited number of locations. A desktop computer is essentially assembled in each home or office—an assembly line of one.

20. This phenomenon is seen in the FAA and IRS systems modernization efforts.

21. In the Standish Group's survey cited earlier in this chapter, respondents blamed incomplete or changing requirements for many of the problems they faced in system development efforts. The more a project's requirements and specifications changed, the more likely it was that the project would take longer than originally planned. And the longer a project took to complete, the more likely it was that the aims of the organization requesting the system would change. In some cases, a project was delayed so long that the larger initiative it was designed to support was discontinued.

22. Indeed, the very notion of sociotechnical systems that is discussed in this report has been more thoroughly investigated outside the United States. U.S. researchers could benefit from more international cooperation. See, for example, Lyytinen (1987).

23. For example, simply upgrading the memory in a personal computer can lead to timing mismatches that cause memory failures that, in turn, lead to the loss of application data—even if the memory chips themselves are functioning perfectly. In other words, the system fails to work even if all of its components work. Similar problems can occur when a server is upgraded in a large network.

24. Architecture relates to interoperability and to ease of upgrading IT systems. A useful definition of the term “architecture” is the development and specification of the overall structure, logical components, and logical interrelationships of a computer, its operating system, a network, or other conception. An architecture can be a reference model for use with specific product architectures or it can be a specific product architecture, such as that for an Intel Pentium microprocessor or for IBM's OS/390 operating system. An architecture differs from a design in that it is broader in scope. An architecture is a design, but most designs are not architectures. A single component or a new function has a design that has to fit within the overall architecture. This definition is derived from the online resource whatis.com (<www.whatis.com>) and is based on Ralston (1976).

25. For decades, financial services have been delivered by organizations composed of elements that themselves are not perfectly trustworthy. Few, if any, of the techniques



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