Capabilities Engineering:Promoting Change-Reduction and Constructing Change-Tolerant Systems

ion levels in Table 3.2. Hence, the CE-based design is the result of an unbiased and systematic construction. Conclusion Validity: This type of validity is concerned with incorrect conclusions drawn about the relationship between the treatment and the outcome. This could arise from violating assumptions of statistical tests, having low statistical power, unreliable measurements and others. The use of a non-parametric test ensures that we fulfill required statistical assumptions. The change-scenarios explained in Section 4.1.3 and the RE/CE-based designs illustrated in Figures 4.2 and 4.1, facilitate the individual verification of the number of impacted classes, thus ensuring reliability. Construct Validity: Construct validity ensures that our research claim is actually investigated in the experiment. It answers the question if the Capabilities-based approach is really responsible for improving the change-tolerance of the system. As presented in Section 4.1.1, the hypothesis tested in the experiment is derived from our research hypothesis. We attempt to establish the relation between the change-tolerance of the system and the design utilized to develop it, by using the same set of change-scenarios on a RE and CE-based design, and explaining the impact of each change in detail. In addition, the changes introduced are realistic and representative of actual user demands. Construct validity also examines if the notion of change-tolerance has been measured accurately. We use the number of impacted classes as an indicator for change-tolerance, a measure that captures the impact of change in a high-level design. External Validity: This type of validity is related to the ability to generalize the result that the use of a Capabilities-based design improves the change-tolerance of all complex emergent systems. We refrain from generalizing these results for all systems. Although, the Course Evaluation System exhibits the desired characteristics for validation, it is a relatively smaller-sized system in the class of complex emergent systems. Furthermore, we