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Cost Savings of Usability Engineering

Usability engineering helps product developers finish their projects on-time and on-budget.

Cost-Benefit Example

The following example shows the benefits of doing a usability study. This example is based on reducing the number of support center calls and increasing employee productivity by producing a better engineered, usability tested product.

Cost of a Usability Study

To 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 Study

To calculate the cost savings after doing a usability study, consider the following:

Calculate support call costs:
Support call $200/call
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 =

$153 million

Usability Engineering Decreases Development Time and Costs

A common myth is that usability engineering adds to development time and costs, but, in fact, the opposite is true:
  • 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].

Usability Engineering Increases Product Sales

Press coverage and product reviews are moving from functionality checklists to usability factors.
  • 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.


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