A statistical study of the relevance of lines of code measures in software projects

Lines of code metrics are routinely used as measures of software system complexity, programmer productivity, and defect density, and are used to predict both effort and cost. The guidelines for using a direct metric, such as lines of code, as a proxy for a quality factor such as complexity or defect density, or in derived metrics such as cost and effort are clear. Amongst other criteria, the direct metric must be linearly related to, and accurately predict, the quality factor and these must be validated through statistical analysis following a rigorous validation methodology. In this paper, we conduct such an analysis to determine the validity and utility of lines of code as a measure using the ISBGS-10 data set. We find that it fails to meet the specified validity tests and, therefore, has limited utility in derived measures.