This Guest paper is valuable to project managers because author Patrick Hankinson draws a clear distinction between the so-called project life cycle (span) and the appropriate "methodology". Methodology is the development process required for managing the creation of the product that is the objective of the project.  While the objective of project management focuses primarily on efficiency in managing time and cost, the objective of product development management is to produce an effective product that satisfies the established need that actually works!
While the project life cycle and the product development methodology have significantly different objectives, nevertheless they ride in tandem through the life span of the project, that is, from the time of starting to the time of completion. Another way of looking at it is that the first overlays the second. It seems that a lot of folks have difficult in grasping this relationship, even to the point of ignoring it.
As Patrick says, his paper is focused on pointing to various "methodology" options available, and while his background is mostly from the Information Technology sector, he makes it clear that these methodologies can be applied in principle to many other project sectors as well.
1. That is, "Product Development Management" as distinct from "Project Management".
2. See also an earlier discussion with Larry Moore in Musings, Part 1 published here: maxwideman.com/musings/methodology1.htm followed by Parts 2 and 3.