Cost Savings of Usability EngineeringUsability engineering helps product developers finish their projects on-time and on-budget.
- Cost-Benefit Example
- Usability Engineering Decreases Development Time and Costs
- Usability Engineering Increases Product Sales
Cost of a Usability StudyTo calculate the cost of a usability study, consider:
- Inhouse usability staff
- Time spent by staff (usability people, developers) x wage rate (same units)
- Additional variable costs (contractors, usability lab rental, travel)
|Cost of inhouse usability staff:|
|Loaded headcount (salary, benefits, vacation time, office space, phones, equipment)||$120,000/year|
|Hours per work year (40 hours/week x 48 weeks)||1,920 hours/year|
|Hourly wage ($120,000/1,920)||$62.50/hour|
|Time spent on usability test by usability engineer (planning, implementation, analysis, recommendations)||160 hours|
|Time spent by interface designer on redesign||60 hours|
|Time spent by development engineers for usability activities||22 hours|
|Total staff costs (160 + 60 + 22 = 242 x $62.50)||$15,125||Costs of a fully-equipped lab:|
|Participant recruiting @ $100/participant (9 participants x $100)||$900|
|Participant compensation @ $50/participant (9 x $50)||$450|
|Videotapes @ $5/each (9 x $5)||$45|
|Percentage of lab and equipment costs = amortized cost of lab/hour ($200/hour x 20 hours)||$4,000|
|Total lab costs||$5,095|
|TOTAL COST of doing a usability study:|
|Staff cost + lab costs = $15,125 + $5,095 = $20,220|
Cost Savings After Doing a Usability StudyTo calculate the cost savings after doing a usability study, consider the following:
|Calculate support call costs:|
|200,000 product Version 1 sold|
|Support calls due to usability problems = 580,000 x $200/call||$116 million|
|Support calls/product sold||2.9 calls/product|
|Usability engineering done on Version 2|
|300,000 product Version 2 sold|
|Support calls to to usability problems = 260,000 x $200||$52 million|
|Support calls/product sold||0.87 calls/product|
|Reduction on support calls||2.03/product|
|Support call cost savings due to increased usability: 2.03 calls/product x 300,000 x $250/call||$152.25 million|
|Calculate increased productivity (inhouse):|
|Task A improved by 3 minutes|
|Task A performed 5 times/day|
|200 users perform Task A|
|Hourly wage (from loaded head count)||$62.50/hour|
|200 users x 3 minutes x 5 = 3,000 minutes saved/day||50 hours saved/day|
|50 hours x $62.50/hour||$3,125|
|Annual amount saved through increased productivity:
$3,125 x 240 work days/year
|Cost of usability study:
|Cost savings after doing a usability study|
(support call cost savings + increased productivity):
= $152.25 million + $750,000 =
- Usability engineering has demonstrated reductions in the
product-development cycle by over 33-50% [Bosert 1991].
- 63% of all software projects overran their estimates, with the top 4
reasons all related to usability [Lederer and Prassad 1992].
- The percentage of software code that is devoted to the interface has
been rising over the years, with an average of 47-60% of the code devoted
to the interface [MacIntyre et al. 1990].
- Ricoh found that 95% of the respondents to a survey never used three key features deliberately added to the product to make it more appealing. Customers either didn't know these features existed, didn't know how to use them, or didn't understand them [Nussbaum and Neff 1991].
- An increased average of 11.2 usability-related comments per software review article [Anderson 1990].
- InfoWorld assigns between 18-30% of its software review articles on 3 usability factors: ease of learning, ease of use, and quality of the documentation [Nielsen 1993].
At Digital, 20 of the most serious usability problems were fixed in the second release of a product. The revenues grew by 80%, which was 66% greater than the projected growth. The customers repeatedly pointed to usability as one of the most significant changes in the product [Wixon and Jones 1991].
The European Community has passed a directive stating:
- "software must be suitable for the task"
- "software must be easy to use"
- "the principles of software ergonomics must be applied" [EEC 1990]
Usability studies can help accomplish these goals.