Inferring Skill from Tests of Programming Performance: Combining Time and Quality

The skills of software developers are important to the success of software projects. Also, when studying the general effect of a tool or method, it is important to control for individual differences in skill. However, the way skill is assessed is often ad hoc, or based on unvalidated methods. According to established test theory, validated tests of skill should infer skill levels from well-defined performance measures on multiple, small, representative tasks. In this respect, we show how time and quality, which are often analyzed separately, can be combined as task performance and subsequently be aggregated as an approximation of skill. Our results show significant positive correlations between our proposed measures of skill and other variables, such as seniority, lines of code written, and self-evaluated expertise. The method for combining time and quality is a promising first step to measuring programming skill in both industry and research settings.