Why it is difficult for a Project Manager to specify how to measure technical performance?

Answer 1

Good project managers recognize their limitations - they don't try to specify detailed requirements for something they don't completely understand. Instead, they lead a collaborative effort by those team members with the right knowledge and experience to get the specifics. For example:

Suppose your project team has been tasked with building a public-facing web site that will be used by potentially thousands of people, simultaneously. Naturally, you want to have an architecture that won't grind to a halt at that load, so you have to find a way to measure performance, from the user's perspective, at different loads. Of course, there is software available that will run various scripts simulating actual user activity at different loads, but the open questions are: what are the acceptable wait times for each feature? what areas of the site do we expect to see the most traffic? should we anticipate an "average" user to have a particular browser, bandwidth, or other characteristic?

These aren't necessarily easy questions,and there's no answer page at the back of the textbook to look them up. So your team might very well need to conduct some experiments to determine what approach to take. After all, you can't manage what you don't measure, but you can certainly mis-manage what you measure poorly.