Does anyone have experience in measuring task success with a TPI score?

As an example I can give measuring task success on a travel website and example tasks would be:

  • Search for a holiday destination I have in mind
  • Filter by date availability
  • View what's included in the deal.

If a maximum score for a task is 100, how do we establish how much to deduct from that depending on the types of struggles a user might have when competing it? Is there an universal formula for this?

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    Hi @pucca, thanks for your contribution to UXSE. I would suggest providing more details about the nature of the tasks that you are trying to evaluate to give people more context about what they have been asked to consider, and perhaps also provide some examples of your thinking process and what your potential formula might look like. This should help the community to respond to the question better. Thanks :) – Michael Lai Oct 2 '18 at 22:29
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    Also, feel free to update your question where you can provide more details instead of the comments :) – Michael Lai Oct 3 '18 at 22:11

Asking for a 'universal formula' to anything is going to be tricky, since it will be either very vague or too exact to be usable.

However, here are a couple of tips to take into consideration when weighing up what to do in the calculations:

  1. Can this be applied consistently to all the other tasks?
  2. Can this be applied consistently to the same task completed by the same user, by different users?
  3. Do all the tasks involve potentially the same type of failure points?
  4. Do all the tasks have similar mechanisms to help the users recover from errors or failures?
  5. Can this be applied consistently to all the types of user testing tasks that you want to compare?
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  • Thanks for your reply! Yes to all of your questions. So I know how much to deduct depending on how long a user takes to complete the task (time penalty - maximum of 40 points) But I struggle to decide how much to deduct on partial successes and failures with confidence, like I have listed above in my other comment. – pucca Oct 3 '18 at 12:21
  • @pucca how did you determine what the time penalty should be? – Michael Lai Oct 3 '18 at 22:11
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    I've been following the practice of Gerry McGovern medium.com/@gerrymcgovern/… – pucca Oct 4 '18 at 9:51

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