It was such a cool idea. The software development industry failed to deliver reliable estimates of tasks. So why not estimate features, or stories with an arbitrary unit. Story Points had been born.
- The basic idea is to create a reference item and then base all estimates as a relation to this reference item. A wonderful approach, because all measurements systems of the world are based on this basic idea. Everything is measured in units that represents a relation to a defined reference.
- What we measure is the SIZE of a Story = Functionality. So we pick a Functionality (any) and then we compare this one with the one we want to measure.
- We say B is x times as big as B.
- DID YOU GET THIS!? …. WE DO NOT… NOT… NOT… NOT COMPARE EFFORT. WE DO NOT ESTIMATE THE EFFORT THAT IS NECESSARY TO BUILD B WITH THE EFFORT THAT IS NECESSARY TO BUILD A.
- We estimate the relation between … the distance between … functionality A and B.
- The XP Gurus 5 years ago tried to explain this by saying. Functionality B is x-times MORE COMPLEX than Functionality B.
- AND then it happend: Developers heard in their minds: To DEVELOP functionality B is x times more complex than functionality B. BUT THIS WAS NOT THE INTENTION.
- Now you are back to effort estimation on task level. And you have the same problem again. Again you talk about an effort to build something. But this is not possible as we can not estimate the effort. (Not even Taylor estimated the effort he measured the effort! … -> well this leads to the next thought. You will see later.)
Repetition: We compare the complexity of a functionality B with the reference complexity of functionality A.
(Read more on Friday)