## Friday, 29 September 2017

### Bulk Estimation at Speed

So, today I faced a new problem. The forecasting I have been using for a while has been throwing out some dates that 'feel' very pessimistic. I want to trust them but they look wrong so I find myself with a dilemma of how to test the forecast in a sensible way.

A previous observation was that whilst asking people how big something is gives a wide range of results whilst asking them if something can be done in a set amount of time is easier to answer and is just as easy to use and interpret as a number.

So given I have a backlog of about 50 things I need to test, I welded these 2 things together and came up with the following session that I ran with my own team.

The only prep you need to do for this is to prepare 2 question cards. The first question is based on the ideal time it should take to do a story. At time of writing, my team want every story to be 5 days or less. So the first question card would be "Will it take 5 days or less?". The second question card, is the opposite extreme of that. So for us, it has gone terribly wrong if it will take 2 or more sprints which is what we have on the second card.

There should be a gap between these which is your middle ground. The observant among you will realise these options look like T-Shirt sizes - which they are! We don't ask that question - we ask is it bigger than X or larger than Y giving a wide difference. If it neither then it must be in the middle ground.

So here's how we ran the session:
Print out your backlog with title and maybe a narrative (as a... I want... so that)
Stack them in the same order as your backlog, highest priority first
Grab a selection of developers and include some QA
Put the question cards and middle ground card on the table
For each card and ask the questions
Expect discussion but keep it short:
* Encourage listing assumptions if that would make it easier to answer, document these if you can
* Re-iterate the ranges using days ("So if you started on Monday, it would be finished by Friday")
* Use comparisons ("Remember that piece of work on X that took 2 sprints, is it as difficult as that?")
* Watch out for unknowns which drive up estimates, mark these for later investigation/refinement
* Use timeboxing if you think it makes sense
Stack the card on the relevant answer card

 Scoring a story whilst telling the story
I was quite surprised as how fast my team did this - 52 stories in 1hr. We can then visualise the backlog in order and colour code the cards to show us the sizes from the team. You would expect first stories to be all green and then progressively turn orange then red as we head further way from the top of the backlog.

That's not what we found.

We found a mix across the backlog that we needed to verify. We discovered that this showed what the team did not have a good understanding of, allowing us to focus our time on refining the cards that were big because we were scared or confused by them.

As far as validating the forecasting, we could now model a series of sprints based on how long they might take which looks a little like a gant chart but is throw away so I will allow it. More importantly it allowed us to see how we might reduce some of the risk in our delivery but tackling the unknowns upfront and ensuring we only develop the smallest stories we can, which are far more predictable.

More importantly, the team found this useful as a confirmation of what we would be doing and in what order allowing them to spot things that had been overlooked. They did this by telling a story of what the system would look like as they developed each story.

They checked the system by also finding places where a demo would make sense and the system would provide end to end functionality that could be seen and understood by stakeholders. We found having a system diagram very useful in this as the developers can point to what they are talking about and everyone understands the context.

They even asked if they could do it again, which is surely the sign of good times :)