Extended SERVQUAL model
Yes, the impact of the first 4 gaps also impact gap 5. The extended SERVQUAL model
actually measures the impact of these interactions, however very few use it.
Most find it easier to use the Gap 5 model but offers little in the way of actionable information. This is a "bounded rationality
" approach to reduce complexity but is ill advised in a complex social context where 1 + 1 does not always = 2 due to synergistic forces which are better assessed using systems-view approaches.
One cannot use difference scores of the RATER dimensions for expectations and perceptions batteries unless the extracted factors are the same. It is also better to confirm scales using SEM before using them for decision-making.
In addition, SEM analyzes all the endogenous and exogenous variable relationships simultaneously which MVA (a subset of SEM) cannot do.
Lastly, many applications of the SERVQUAL model fail to assess rigorous data screening methods for MV applicability which can affect data usefulness.