Reliability of COSMIC Functional Size Measurement Results: A Multiple Case Study on Industry Cases

Accuracy of the functional size is critical in software project management, since functional size is the most prevalent input for effort and cost estimation models. Functional size measurement is performed based on standardized manuals; however, the accuracy of FSM results is still based on the knowledge and cautions of the measurers. In this study we performed a multiple case study to identify the reliability of COSMIC and to observe the frequently encountered errors during functional size measurement. Problems in the individual learning process and the clarity of the guidelines are distinguished as the two main causes that impact the accuracy of the measurement results.