If we have 2 user stories (A and B), I can say A is smaller than B hence, A is less story points compared to B.
But what does “smaller” mean?
- Less Complex to Understand
- Smaller set of acceptance criteria
- Have prior experience doing something similar to A compared to B
- Have a rough (better/clearer) idea of what needs to be done to implement A compared to B
- A is less volatile and vague compared to B
- and so on…
So, A is less story points compared to B. But clearly we don’t know how much longer its going to take to implement A or B.
Hence we don’t know how much more effort and time will be required to implement B compared to A. All we know at this point is, A is smaller than B.
It is important to understand that Story points are relative complexity estimate NOT effort estimation (how many people, how long will it take?) technique.
Now if we had 5 stories (A, B, C, D and E) and applied the same thinking, we can come up with different buckets in which we can put these stories in.
Small, Medium, Large, XL, XXL and so on….
And then we can say all stories in the small bucket are 1 story point. All stories in medium bucket are 3 story points, 5 story points, 8 story points and so on…
Why do we give these random numbers instead of sequential numbers (1,2,3,4,…)?
Because we don’t want people to get confused that medium story with 2 points is 2 times bigger than a small story with 1 point.
We cannot apply mathematics or statistics to story points.