The most fundamental difference between auditing and evaluation concerns theory. All types of evaluation are underpinned by theory. This applies both to theories of what is being evaluated and theories about evaluation. If we install a technology, such as an intranet into an organisation, a robot into a production line or an MRI scanner into a hospital, we do so based on a theory, or theories, of how this technology delivers intended or observed outcomes. The same applies to projects and programmes, where theory informs our beliefs and assumptions about how the project or programme should operate and what might be the planned and actual outcome.
The function of auditing is much more constrained. It concerns checking what actually happens as a result of a technological development, project or programme ‘... against prescribed normative standards ... [such that] The information provided by an audit can be considered to be evaluative insofar as equalling or surpassing a predicted target figure is deemed preferable to falling beneath it’ (Clarke, 1999, p. 5).