Over the past several decades, sof.twaremaintenance has heen absorbing a large and rising proportion of Information Systcmns (IS) resources wilh expenditures ofteu as high as 80% to 95% of the total IS budget (Nosek and Palvia 1990). On a life-cycle basis, about three-fourths of the investment in software occurs after the system bas been implemented. Thus, support for existing software represents il significant investment of resources for most f m s and there is considerable interest in understaiding and improving productivity and quality in the software maintenance w k .