Investigating measurement scales and aggregation methods in SPICE assessment method
This study identified three issues in SPICE (Software Process Assessment and Capability dEtermination) assessment method based on ISO/IEC 15504-2 (Performing an assessment). The issues include a lack of a measurement scale for characterizing the extent to which an outcome (practice) is achieved (implemented) and two shortcomings of the aggregation methods in order to generate a process attribute (PA) rating. Such issues may be weaknesses to the needs of retaining consistent assessment results comparable within and across assessed organizations. The purpose of this study is to identify issues, such as the measurement scale and aggregation methods, in SPICE assessment methods and to provide candidate solutions based on measurement theories, while the rating scales of the current PA and capability are retained. For those purposes, the present study reviews scale types based on a measurement theory and uses the reflective and formative measurement models in order to find the relationships between PAs and practices. Composite measure development methods that are dependent on the relationships are then proposed on the basis of appropriate aggregation methods by using multiple attribute decision making (MADM) methods. Six candidate solutions are presented along with their strengths and weaknesses based on practical and theoretical perspectives. Two examples are given to illustrate and interpret six candidate solutions for the issues identified. By applying six candidate solutions to the examples shows that the measurement scale and the aggregation methods influence the PA rating. The process community, including the SPICE standardization group, can initiate discussions in order to determine the measurement scale and the aggregation methods with our six candidate solutions. The rationale and methods addressed in this study can also be applied to other domains in order to derive a composite (aggregate) value or rating.
aggregation method spice formative measurement model madm iso/iec 15504 reflective measurement model