weekly discussion 500 words (complex projects)

In chapter 6 of Terry Cooke-Davies' book Aspects of Complexity Dale Shermon promotes parametric estimating as the means of being able to estimate a certain type of complex project (Cooke-Davies 2011, p.76-79).  However, the examples he uses are all related to engineering type projects.

Is the methodology of parametric estimating appropriate to projects in the non-engineering domain, such as welfare projects?  Is so then how is that the case?  If not then why is that the case?