“The Stacey Matrix was developed to help managers determine the complexity of their environment and adapt their style of decision-making. For software development, the Matrix is often plotted along different axes; ‘Requirements’ and ‘Implementation’ (or ‘Technology’). The former is determined by the obviousness to which we know what we need to build (like the product) and what features to implement (‘What?’), whereas the latter is determined by the obviousness of what is needed to get there on in terms of implementation/technology (‘How?’). It should be noted that this adaptation does not really fit with Stacey’s original Matrix. But it does offer a similar conceptual approach to understand complexity within the context of software development, and what approach to use.”
from On Complexity (Stacey & Cynefin): Why Your Software Project Needs Scrum
English