This was the first attempt to measure quality of service.
Gronroos model was general and without offering any technique on measuring technical and functional quality.
Rust & Oliver (1994) tried to refine the Nordic model by The Three-Component Model.
They suggest three components: service product (i.e., technical quality), service delivery (i.e., functional quality), and service environment but they did not test their model and just a few support have been found.