Abstract: Measuring maintainability near the beginning in the software development life cycle, particularly at design phase, may help the designers to integrate required improvement and corrections for improving maintainability of the developed software. This study developed a multivariate regression model ‘Maintainability Estimation Model for Object-Oriented design’ at Design phase in software development process. Developed model measures the maintainability of object oriented design in respect of Extendibility and Flexibility. Though, in order to quantify object oriented design’s Extendibility and Flexibility the study required to develop two more models. These two models use design level object-oriented metrics, to quantify Extendibility and Flexibility of class diagram. Maintainability measurement in early stage of development cycle facilitates the designers to improve the maintainability of class diagram and consequently the maintainability of software. All the developed models have been empirically validated through proper statistical measures and contextual explanation has been drawn.

Keywords: Maintainability, Estimation, Metrics, Object Oriented Design.