The Home Office commissioned us to ensure the usability of the £93 million National Automated Fingerprint Identification System (NAFIS). NAFIS will provide fingerprint matching facilities for all 43 police forces in England and Wales. The usability challenge was to ensure that fingerprint officers—whose exposure to computers is often slight—could use the system.

Work on this project involved every aspect of usability engineering. For example, we:

• Developed an hierarchical task model of the fingerprint officer's job;
• Proved the importance of HCI to software engineers;
• Agreed real, complete, representative tasks to evaluate the system;
• Carried out heuristic analyses and cognitive walkthroughs of early prototypes;
• Determined usability benchmarks;
  Tested prototypes in a purpose-built usability lab;
• Collected data to show the cost-benefit of usability testing.

To carry out the work we designed and managed the construction of a fully equipped usability laboratory containing an extensive range of audio and visual recording equipment. Working as part of the client's usability team, we completed two rounds of usability testing in this lab. We used the lab to observe fingerprint officers using NAFIS and we took precise measurements of their performance, both from videotape and in real time. These results were compared with usability benchmarks, which were used to quality assure the final system.