Scientists write and maintain software artifacts to construct, validate, and apply scientific theories. Despite the centrality of software in their work, their practices differ significantly from those of professional software engineers. We sought to understand what makes scientists effective at their work and how software engineering practices and tools can be adapted to fit their workflows. We interviewed 25 scientists and support staff to understand their work. Then, we constructed a theory that relates six factors that contribute to their efficacy in creating and maintaining software systems. We present the theory in the form of a cycle of scientific computing efficacy and identify opportunities for improvement based on the six contributing factors.
