Silvio Stefanucci

Assessing effort estimation models for corrective maintenance through empirical studies

Abstract We present an empirical assessment and improvement of the effort estimation model for corrective maintenance adopted in a major international software enterprise. Our study was composed of two phases. In the first phase we used multiple linear regression analysis to construct effort estimation models validated against real data collected from five corrective maintenance projects. The model previously adopted by the subject company used as predictors the size of the system being maintained and the number of maintenance tasks. While this model was not linear, we show that a linear model including the same variables achieved better performances. Also we show that greater improvements in the model performances can be achieved if the types of the different maintenance tasks is taken into account. In the second phase we performed a replicated assessment of the effort prediction models built in the previous phase on a new corrective maintenance project conducted by the subject company on a software system of the same type as the systems of the previous maintenance projects. The data available for the new project were finer grained, according to the indications devised in the first study. This allowed to improve the confidence in our previous empirical analysis by confirming most of the hypotheses made. The new data also provided other useful indications to better understand the maintenance process of the company in a quantitative way.

Assessing the maintenance processes of a software organization: an empirical analysis of a large industrial project

The use of statistical process control methods can determine the process capability of sustaining stable levels of variability, so that processes will yield predictable results. This enables to prepare achievable plans, meet cost estimates and scheduling commitments, and deliver required product functionality and quality with acceptable and reasonable reliability. We present initial results of applying statistical analysis methods to the maintenance processes of a software organization rated at the CMM level 3 that is currently planning the assessment to move to the CMM level 4. In particular, we present results from an empirical study conducted on the massive adaptive maintenance process of the organization. We analyzed the correlation between the maintenance size and productivity metrics. The resulting models allow to estimate the costs of a project conducted according to the adopted maintenance processes. Model performances on future observations were assessed by means of a cross validation which guarantees a nearly unbiased estimate of the prediction error. Data about the single phases of the process were also available, thus allowing to analyze the distribution of the effort among the phases and the causes of variations.

Effort estimation for corrective software maintenance

This paper reports on an empirical study aiming at constructing cost estimation models for corrective maintenance projects. Data available were collected from five maintenance projects currently carried out by a large software enterprise. The resulting models, constructed using multivariate linear regression techniques, allow to estimate the costs of a project conducted according to the adopted maintenance processes. Model performances on future observations were achieved by taking into account different corrective maintenance task typologies, each affecting the effort in a different way, and assessed by means of a cross validation which guarantees a nearly unbiased estimate of the prediction error. The constructed models are currently adopted by the subject company.

Managing coordination and cooperation in distributed software processes: the GENESIS environment

We present the GENESIS platform (GEneralised eNvironment for procEsS management in cooperatIve Software engineering), the outcome of a research project aiming at designing and developing a noninvasive and open-source system to support software engineering processes in a highly distributed environment. The system supports the cooperation and coordination in software processes as its process modeling language enables the decomposition of complex processes into subprocesses that can be distributed and executed at different organizational sites. In GENESIS, workflow management technologies have been integrated with artifact management and communication services to meet the necessary requirements of managing the cooperation among distributed teams. Its strengths are a powerful activity management, covering all the main aspects of the life cycle of an activity; an efficient and flexible project monitoring, collecting productivity and quality metrics to show on-demand snapshots of the whole process and of its parts at different levels of detail, and a careful consideration of the process evolution questions, allowing to adequately manage the most common exceptions happening during process execution in a simple and flexible way. Copyright

Understanding SQL through iconic interfaces

Visual query languages represent an evolution, in terms of understandability and adaptability, with respect to traditional textual languages. We present an iconic query system that enables the interaction of a novice user with a relational database. Our goal is to help a novice user to learn and comprehend the relational data model and a textual query language such as SQL, through the use of the iconic metaphore. In this sense our approach is different from most of the visual query systems proposed in the literature that present the user with a higher level query language, hiding the underlying data model. We also present results from an experiment conducted with first year students to evaluate the effectiveness of our approach.

Introducing workflow management in software maintenance processes

Software organizations are moving from traditional software factory models towards virtual organization models, where distributed teams converge in a temporary network with the aim of integrating different competences or solving problems in a cooperative way. Most workflow management systems of last generation are web based and this makes them a viable enabling technology for remodeling both the organization structure and its processes in order to move towards a virtual organization model and increase its competitiveness. We present a case study of introducing workflow technologies in a large software enterprise. In particular, a workflow-based prototype implementation for the management of the ordinary maintenance process is discussed.

Early effort estimation of massive maintenance processes

Effort estimation is a valuable asset to managers in planning maintenance activities and performing cost/benefit analysis. Early estimates and accurate evaluations permit to significantly reduce project risks and to improve resource scheduling. In this paper we present an approach for an early effort estimation based on the knowledge of a fraction of the programs composing the work-packet. As a case study, the proposed approach has been applied to a large massive maintenance project performed by a major international software enterprise.

Assessing massive maintenance processes: an empirical study

We present an empirical study from the experience of a major. international software enterprise in conducting massive adaptive maintenance projects with a close deadline. The adopted process entails the decomposition of the application portfolio into loosely coupled work-packets that can be independently and incrementally worked out by teams distributed on different sites. The study analyzes the correlation between maintenance size and productivity metrics of a large Y2K project. The resulting models allows to estimate the costs of a project conducted according to the adopted massive maintenance process and distribute them among the different phases.

Understanding and improving the maintenance process: a method and two case studies

The skill shortage and the increasing dynamism of the global market with the consequent needs for achieving market differentiation, focussing on core competences and reacting faster on changes in the environment, are forcing software enterprises to move towards a virtual organization. Workflow and computer supported cooperative work technologies are a primary enabler for virtual organizations, as distributed teams of software engineers make substantially more use of computer mediated channels than physical presence to interact and cooperate in order to achieve their objectives. A preliminary step for introducing workflow technology into a software organization is comprehending the existing processes with the aim of modeling, analyzing, and redesigning them. This paper illustrates a method to approach the comprehension in a systematic way and discusses key issues and lessons learned from two case studies.

Evolving Ispell: a case study of program understanding for reuse

Text processing has proven helpful in a number of software engineering tasks. We discuss how a morphological analyser for the Italian language, and its associated linguistic resources, have been developed by reusing and evolving an existing system, Ispell, which is an open-source spell-checker. The need to develop such an analyser derives from the need to improve the traceability link recovery process described by G. Antoniol et al. (2000, 2002). This paper shows how the program understanding exercise was useful to develop a system in a specialized application domain in which we had a very limited background knowledge.