  Although software managers are generally good at new project estimation,
their experience of scheduling rework tends to be poor. Inconsistent or
incorrect effort estimation can increase the risk that the completion time for
a project will be problematic. To continually alter software maintenance
schedules during software maintenance is a daunting task. Our proposed
framework, validated in a case study confirms that the variables resulting from
requirements changes suffer from a number of problems, e.g., the coding used,
end user involvement and user documentation. Our results clearly show a
significant impact on rework effort as a result of unexpected errors that
correlate with 1) weak characteristics and attributes as described in the
program's source lines of code, especially in data declarations and data
statements, 2) lack of communication between developers and users on a change
effects, and 3) unavailability of user documentation. To keep rework effort
under control, new criteria in change request forms are proposed. These
criteria are shown in a proposed framework; the more case studies that are
validated, the more reliable the result will be in determining the outcome of
effort rework estimation.
