This paper develops a model of software process improvement, based on the systems approach and soft systems methodology and an adapted version of GQM to allow for qualitative metrics. The product characterisation from soft systems methodology causes a difficulty as it does not consider time.
Bennetts, Peter D.C. and Wood-Harper, A. Trevor, "Soft Systems Methodology - A Foundation for a Systematic Approach to SPI" (2000). AMCIS 2000 Proceedings. 369.