> there's a good chance one of them knows something the other does not
Or that the assignment of points is arbitrary and imprecise and that different people have different ways of making up numbers.
Or that the assignment of points is arbitrary and imprecise and that different people have different ways of making up numbers.
Instead of worrying about 5 vs 8 though, the team should be discussing relative difficulty: is story B easier/more difficult/complex than story A? And then ranking stories based on the relative difficulty of each other.
Story points can then be derived based on that ranking, if the team chooses. They're useful for being applied to velocity calculation, and also helpful when picking up a story to work on (maybe a bad idea to start an 8 pointer on a Friday).
(I have a SM cert, working as a TPM. I applying Agile principles to teams, but modified to how they want to work and be most effective. No militant Scrum here.)
As for its usefulness: You of course don't have to necessarily poker to get these discrepancies, but it's a pretty effective way of going about it, I'd say.
Second, the numbers _are_ arbitrary. Completely, 100% arbitrary. It's a _relative_ difficulty scale. Say you've got 3 tasks - A, B, and C. A and B are approximately as hard as each other, they're 1 story point. C is more difficult than either one - it gets 2 points. That's it. Story points are not, and should not be used as, a unit of measurement. The biggest utility is to identify big, scary tasks with lots of unknown factors.
The fact that they are _numbers_ is what tricks so many teams/PMs/management/etc into thinking that story points are more meaningful than they were ever supposed to be. Incidentally, this is also why some planning poker teams use t-shirt sizing (S,M,L,XL,XXL, etc). No numbers means people are less tempted to punch them into a spreadsheet while deluding themselves into believing that showing numbers going down is the same thing as "showing progress".
At least that is the idea.