Context: The usability software quality characteristic aims to improve system user performance. In a previous study, we found evidence of the impact of a set of usability features from the viewpoint of users in terms of efficiency, effectiveness and satisfaction. However, the impact level appears to depend on the usability feature and suggest priorities with respect to their implementation depending on how they promote user performance.Objectives: We use a family of three experiments to increase the precision and generalization of the results in the baseline experiment and provide findings regarding the impact on user performance of the Abort Operation, Progress Feedback and Preferences usability mechanisms.Method: We conduct two replications of the baseline experiment in academic settings. We analyse the data of 366 experimental subjects and apply aggregation (meta-analysis) procedures.Results: We find that the Abort Operation and Preferences usability mechanisms appear to improve system usability a great deal with respect to efficiency, effectiveness and user satisfaction.Conclusions: We find that the family of experiments further corroborates the results of the baseline experiment. Most of the results are statistically significant, and, because of the large number of experimental subjects, the evidence that we gathered in the replications is sufficient to outweigh other experiments.

Usability is a software system quality attribute. Although software engineers originally considered usability to be related exclusively to the user interface, it was later found to affect the core functionality of software applications. As of then, proposals for addressing usability at different stages of the software development cycle were researched. The objective of this paper is to present three reusable solutions at detailed design and programming level in order to effectively implement the Abort Operation, Progress Feedback and Preferences usability functionalities in web applications. To do this, an inductive research method was applied. We developed three web applications including the above usability functionalities as case studies. We looked for commonalities across the implementations in order to induce a general solution. The elements common to all three developed applications include: application scenarios, functionalities, responsibilities, classes, methods, attributes and code snippets. The findings were specified as an implementation-oriented design pattern and as programming patterns in three languages. Additional case studies were conducted in order to validate the proposed solution. The independent developers used the patterns to implement different applications for each case study. As a result, we found that solutions specified as patterns can be reused to develop web applications.