Title: The mirroring hypothesis
Description: The mirroring hypothesis asserts that the organizational patterns of a development project (e.g. communication links, geographic collocation, team and firm co-membership) will correspond to the technical patterns of dependency in the system under development. Thus the hypothesis predicts that developers with few or no organizational linkages will design independent system components, while developers with rich organizational linkages will co-design highly interdependent system components. (The hypothesis claims a correspondence between organizational structure and technical architecture, but allows causality to flow in either direction.) In this paper, we formally define the mirroring hypothesis, describe its theoretical underpinnings and systematically review the empirical evidence for and against it. Our review includes 129 studies spanning three levels of organization: within a single firm, across firms, and open community-based development. Across these levels, the hypothesis was supported in 69% of the relevant cases, but not supported in 31%. It was most strongly supported within firms, less strongly across firms, and often violated in community-based development settings.