When best to perform a heuristic evaluation?

Question

I am currently introducing industry standard usability practices & processes into our software development cycle.

The following prototype phase has been introduced which consists of the following

1. (Parallel Design) Lo-fi Wireframe (3 Versions)

2. Usability Testing on Wireframes

3. Prototype Wireframe based on merged wireframes & usability testing feedback

4. Prototype Usability Testing

5. Prototype Iteration 1

6. Prototype Usability Testing Prototype Wireframe

7. Prototype Iteration 2

This prototype process is for the development of new software products. When would be best to perform an Heuristic Evaluation.

Additionally is this prototype phase ideal? Would it also work for an existing software?

I'm merely after professional opinions and pointers here, Positive or Negative.

I'm entering the world of UX and want to follow the best practices.

Answer 1

Evaluating your design through established usability heuristics is cheaper than conducting usability tests. Therefore it's a good idea to have an evaluation of each design before a usability test to ensure that the result isn't spoilt because of a trivial(or non-trivial) design choice, which could have been avoided through an evaluation.

Answer 2

A heuristic evaluation is not necessarily cheaper than a usability test. A heuristic evaluation requires 3-5 usability professionals because of the evaluator effect. Personally, I only have 2 usability experts at my company (including myself). Ideally, I would have 3-5 reviewers including at least one senior usability expert and one junior usability person. All would uncover different issues. I would also suggest including some subject matter experts (non-usability people).

“One of the biggest criticisms of HE is that it tends to uncover many low-severity problems or issues that aren't really problems (false positives). An additional practical problem is that multiple usability experts should be used. It can often be more expensive and difficult to find 3-5 usability professionals as it is to test 3-5 users.” - Jeff Sauro, 8/2/11

However, an expert review should be done before a usability test to make sure you will get good results and avoid trivial design choices. I would also suggest a pilot study (~2 users) before the usability test (~5 users per persona/profile).

My best advice is to use a variety of inspection methods (i.e. triangulation) to uncover most of the issues. Instead of just usability testing, consider expert reviews (or cognitive walkthroughs), heurisic evaluations and usability testing.