Heuristic evaluations are suited for early in the usability engineering life cycle. Since evaluators are not quite using the system to perform a real task, heuristic evaluations can be performed on user interfaces that exist on paper only and have not yet been implemented [7,11,12,13,14]. Even though the interface does not have to be implemented in order to perform a heuristic evaluation, the user interface design does have to be generated.
Early work speculated that heuristic evaluation might be easier for interfaces with a high degree of persistence [11]. Paper prototypes are more persistent than running interfaces. Although, problems relating to a missing interface element are harder to find when an interface is evaluated as a paper prototype. On running systems, this problem was just as easy to find as other ones [11].
To get an idea of how heuristic evaluation can be incorporated with user testing in the design and evaluation process of an interface, skip to "Heuristic evaluations and other evaluation techniques".