Experimental use of code delta, code churn, and rate of change to understand software product line evolution

This research is a longitudinal study of change processes. It links changes in the product line architecture of a large telecommunications equipment supplier with the company’s customers, inner context, and eight line card products over six-year period. There are three important time related constructs in this study: the time it takes to develop a new product line release; the frequency in which a metric is collected; and the frequency at which financial results and metrics related to the customer layer are collected and made available. Data collection has been organized by product release. The original goal of this research is to study the economic impact of market reposition on the product line and identify metrics that can be used to records changes in product line. We later look at the product line evolution vis-à-vis the changes in the products that form the product line. Our results show that there is no relationship between the size of the code added to the product line and the number of designers required to develop and test it; and there is a positive relationship between designer turnover and impact of change.