Glaser suggests that although theory can be generated directly from data, that:
“it is most desirable, and usually necessary, to start the formal theory from a substantive one. the latter not only provides stimulus to a “good” idea, but it also gives an initial; direction in developing relevant categories and properties and in choosing possible modes of integration.” – p79
There are processes by which a substantive theory can be andvanced to a formal one.
I could extrapolate a generalisation beyond my case studies. E.g. instead of saying something like “the architectural elements applied by soilless farmers of x farm in Eindhoven, Netherlands” – I could say “the architectural elements of soilless farming”. This is a change of focus from substantive to formal. However this would only really make a start on creating a new theory – as I “won’t have escaped the time and place” of my substantive research, though my “formal theory may lead readers into thinking so” – p81
Where substantive theory is a fit for some case of reality – the formal theory borrowed from it, may only fit poorly in general. (p81). Another risk here is that the data and the theory become detached and that the connections between the theory and data aren’t clear.
However that doesn’t make it bad – it’s just important to recognise that this theory needs to be developed – via comparative analysis with other substantive areas to make it generally applicable / robust. I.e to start to discuss “the architectural elements of soilless farming” I would need to undertake comparative analysis of other aspects of soilless farming than just one case study.
Barney G. Glaser & Anselm L. Strauss. 1967. The Discovery of Grounded Theory. London: Weidenfeld and Nicolson.