Discount usability evaluation was also developed by Nielsen in 1989. The idea behind this technique is to enable developers with few resources - in terms of time, money, or expertise - to benefit from usability testing during product design and development. In particular, the method was geared towards small companies that cannot afford full-scale usability testing like that used in usability engineering.
In Nielsen's words, "The discount usability engineering method consists of scenarios, simplified thinking aloud and heuristic evaluation and is intended to alleviate the current problem where usability work is seen as too expensive and difficult by many developers".
Discount usability engineering is thus really a hybrid of empirical usability testing and heuristic evaluation. The first part of the method uses usability testing and involves the construction of scenarios, which are tested using "think-aloud" protocols. Interestingly, often only one to three subjects take part in this testing phase. On the basis of the results obtained from this yet the scenario is changed and tested again. The second part of the method involves testing the scenario using the heuristic evaluation method described above.
The features that result in important discounts include:
The scenarios are small and so can be changed easily - mockups are often used.
The think-aloud method is done informally and does not require psychologists,
Just a few key guidelines are used rather than the large number available - the nine guidelines listed above were found to be ample for the purpose,
The whole cycle need only involve two or three testers since the number of additional usability problems found by more testers was not worth the extra effort.
An example of discount usability engineering
A Danish bank (Nielsen, 1989) wished to improve its bank account statements, so it planned to redesign them. At the beginning of the redesign a vocabulary study was performed on the original version of the statements, which identified 26 words, and 30 people were asked to rate these words according to how well they understood their meaning. Of the 26 words, 7 were difficult to understand, as the "think-aloud" method alter confirmed. The statements were then redesigned and several iterations of discount design-test-redesign were carried out using well-known usability heuristics such as "consistency". In this study, a total of 8 different versions of the account statements were tested. However, the whole study was reported to take only 90 person-hours, including the design of 7 different versions of 12 different kinds of bank statements.