Task Performance Indicator - TPI

"You can't manage what you don't measure"

Our Task Performance Indicator measurements help you improve the time it takes users to complete key tasks. We create a scorecard for how efficient your intranet or website is for your users.

We start by creating a baseline. Based on our observations of users, we create general and task specific suggestions for significant user interface improvement. When you have implemented improvements, we measure again to ensure that the improvements work.

Example: Our measurements could show that it takes users 35 seconds to find the telephone number of a colleague using your intranet. Based on our experience, we suggest a realistic user interface improvement that reduces this time to 12 seconds. When you have implemented our recommendation or your own alternative, we measure again. In this way, you can objectively determine if you get value for your usability investments.

To obtain reliable results we measure each top task with 15-20 users. Each user carries out 10-20 tasks as quickly as possible under realistic conditions. We observe what users do. The measurements take 30-90 minutes for each user.

Our report provides:

• Average time for users to solve realistic, frequent tasks.

• Success rate - percentage of users who solve the task correctly.

• Disaster rate - percentage of users who encounter a "disaster" - that is, they find a seriously wrong answer but believe that it is correct.

• Task Performance Indicator (TPI) - one usable figure that summarizes the previous three measures.

• Optimal paths - realistic recommendations for improving the TPI substantially, if possible.

You can use DialogDesign's report to:

• Systematically measure the effects of your development efforts on the user interface and track progress.

• Reward employees who are responsible for tasks whose TPI improves significantly. With the TPI approach you reward based on objective measurements rather than random, subjective opinions.

More about Task Measurement on www.Customercarewords.com where you can find Gerry McGovern's description of the method. Gerry McGovern from Customer Carewords conceived the method. Rolf Molich from DialogDesign developed and implementered it.