Page 533 -

532 Part Four Building and Managing Systems

prepared. After the system has been fine-tuned, it must be maintained while
it is in production to correct errors, meet requirements, or improve process-
ing efficiency. Changes in hardware, software, documentation, or procedures
to a production system to correct errors, meet new requirements, or improve
processing efficiency are termed maintenance.
Approximately 20 percent of the time devoted to maintenance is used for
debugging or correcting emergency production problems. Another 20 per-
cent is concerned with changes in data, files, reports, hardware, or system
software. But 60 percent of all maintenance work consists of making user
enhancements, improving documentation, and recoding system components
for greater processing efficiency. The amount of work in the third category of
maintenance problems could be reduced significantly through better systems
analysis and design practices. Table 13.2 summarizes the systems develop-
ment activities.

MODELING AND DESIGNING SYSTEMS: STRUCTURED
AND OBJECT-ORIENTED METHODOLOGIES

There are alternative methodologies for modeling and designing systems.
Structured methodologies and object-oriented development are the most
prominent.

Structured Methodologies
Structured methodologies have been used to document, analyze, and design
information systems since the 1970s. Structured refers to the fact that
the techniques are step by step, with each step building on the previous
one. Structured methodologies are top-down, progressing from the highest,
most abstract level to the lowest level of detail—from the general to the specific.
Structured development methods are process-oriented, focusing primarily
on modeling the processes, or actions that capture, store, manipulate, and dis-
tribute data as the data flow through a system. These methods separate data

TABLE 13.2 SYSTEMS DEVELOPMENT

CORE ACTIVITY DESCRIPTION
Systems analysis Identify problem(s)
Specify solutions
Establish information requirements
Systems design Create design specifications
Programming Translate design specifications into program code
Testing Perform unit testing
Perform systems testing
Perform acceptance testing
Conversion Plan conversion
Prepare documentation
Train users and technical staff
Production and maintenance Operate the system
Evaluate the system
Modify the system

MIS_13_Ch_13 global.indd 532 1/17/2013 2:31:22 PM