GQM based Inspection

Inspections are generally accepted as a means to improve the quality of software products in an effective and efficient way. However, inspections are not a standard practice in a great number of software projects and software organisations. Introducing and implementing inspections is often a tedious and difficult task, because software engineers must be personally convinced of the effectiveness of new methods before they will consistently use them. Collecting relevant data during inspections is a way to overcome these difficulties. Such data collection for software inspections is termed measurement. Measurement is a powerful aid to implement and improve the inspection process. Showing real-life data is often convincing for both the software engineers and their managers. A well-known and popular software measurement approach is the Goal/Question/Metric method (GQM). Applying GQM to the inspection process helps to focus the data gathering process, and support the interpretation process. An important part of the measurement programme and thus inspection implementation and improvement process are the so-called feedback sessions. Feedback sessions are meetings involving members of the project team and the measurement team. It is an essential tool for analysis and interpretation of the measurement results. The background to this paper is the implementation of inspections in a number of Dutch organisations using the GQM approach as a main vehicle. Practical examples are provided of the measurement goals, metrics and feedback sessions. 1. Software Inspections In every software development phase defects are introduced, found and rework is being carried out. However, often most defects are only found when the software product is almost finished, e.g. during the system and acceptance testing phase, or even during operation. Defects found during the testing phase have the disadvantage that their rework on the almost finished software product is very time consuming. It would have saved the development organisation a lot of time if these defects where found during an earlier development phase. Inspections are an effective and efficient measure that can be introduced to improve the quality of the products at an early stage [2]. Besides finding a defect at the earliest possible moment, the prevention of defects is the important issue. Inspections can also be used as a means for defect prevention. Based on an analysis of the defects that were found, the software development processes can be adapted and optimised to prevent these defects from occurring in the future (as far as possible). Engineers that are involved in the inspection process can learn from their defects or the defects that were made by someone else. Inspections can be defined as a structured review of an engineers’ software work product carried out by his colleagues to find defects and to enable the engineer to improve the quality of the product [1]. While the importance and benefits of inspections for software projects is well understood within the software industry, only few engineers apply the inspection technique to their personal work. Even when statistic evidence from other organisations and projects exists [4] [7], the introduction of improved software methods, e.g. inspections, is often slow because