When deciding requirements for a project, we're often trying to decide priorities between many items. This rapidly becomes difficult to do in your head ("or in your heads" in a meeting). Here's a useful tool, the prioritizing grid.
It originally comes, I think, from Richard N Bolles, author of "What Color is your Parachute" (a manual for job-hunters and career changers). Career counsellor and consultant Beverly Ryle has an interactive version on her website. The original purpose is to rank skills that a person has (e.g. "I am good at writing and also at cooking, particle physics and kung-fu, but which of these do I like doing best?"). In its original context it is part of an exercise to help identify careers that a person is likely to find they'd enjoy. But the system could be used for prioritizing any kind of things - here is a screenshot of it in use to prioritize features of interest when choosing a car.
The way it works is that you write out the things you want to prioritize in any order, and number them 1-10 (if there should happen to be 10). In the screenshot, the un-prioritized items are listed on the left. Then you work through them in pairs like this:
- Which do I prefer, 1 or 2?
- Which do I prefer, 1 or 3?
- Which do I prefer, 1 or 4?
Once done with number 1, you do the same with 2:
- Which do I prefer, 2 or 3?
- Which do I prefer , 2 or 4?
and then you move onto number 3:
- Which do I prefer, 3 or 4?
- Which do I prefer, 3 or 5?
...and then with each of the other factors until you reach the last pair.
It sounds cumbersome, but actually does not take at all long, unless you are over-thinking it, or need to define the factors better, or have a lot of items that you don't care about much.
Once you're done, you go through each factor and you count up the number of times you preferred it to something else. This gives you the rank order.
In the screenshot example I've done that (the website has pairs of radio buttons to indicate your choice, but you could of course do this on a piece of paper....). On the right of the screenshot you see the priority order that this generates. It looks like I want a car that seats 4 passengers, has plenty of boot ("trunk" to US readers) space, is cheap on fuel and hard to steal (family life in Oxford...).
As with anything else, I'd say "don't let the tool take over". Perhaps you don't really have a preference between a pair, or can't answer until the items are better defined. Either of those discoveries could be useful - probably more useful than forcing everything artificially into neat priorities in order just to get the worksheet done.