Story Points
A cornerstone of Agile Estimating and Planning.
And also the source of much confusion.
Not least for me.
I didn’t understand them for the longest time.
But now, at last, the mists are clearing
Welcome to Development The Pays
My name is Gary Straughan
And welcome back to this mini series on
Agile Estimating and Planning
If you’d like to catch up
This link will take you right to the beginning
and deliver you automagically…
Right back to the this very point.
All caught up?
Let’s dive in!
This is a map of Great Britain.
Notice anything strange about it?
Not really a fair question.
I grew up colouring in pictures of this map at school
For those of you that didn’t
This is a more conventional view of Great Britain
The reason for this distortion?
This is not a map of DISTANCE
it’s a map of TIME.
The map represents travel time.
More specifically: travel time from London.
(This kind of map is called an Isochrone in case you want to Google for a map of your
own country or region.)
The stretching that we see in Scotland And the southwest
And parts of the east
Is a reflection that the transport system in these areas
is less well developed.
Which, is no bad thing.
Would you build a motorway through this?
For planning a trip, this map is excellent:
I get to see directly how long it will get somewhere.
With no nasty surprises
(Like the one I got the first time that I drove to the Highlands of Scotland.)
I like this map a lot
But there are a couple of drawbacks to this map
that you’ve probably already spotted.
This version represents travel time from/to London.
Great for me, because I live in London.
Not so good for someone who lives in Galsgow
They would need a different version.
There are potentially an infinite number of these maps
each with a different starting point.
That’s one problem.
Another is that whoever put together this map
made assumptions about the mode of transport.
Is this a map of travel times for car travel?
or public transport?
The shape of the map will be different in each case.
It would be different again for walking
and for cycling.
So it turns out that this style of map isn’t as useful as it might look at first sight.
The conventional map turns out to be more useful
even though it doesn’t give me the number I want directly.
I want travel time,
What I get is distance
But I’m very comfortable with “deriving” time from distance.
And I bet you are too.
It's second-nature to us
To take a distance and “transmute” it into time.
Let's do a quick demonstration of that
If I ask you how long it takes to drive from Paris to Brussels…
You may not have the first idea.
If I tell you they are 317 km apart
( that’s just short of 200 miles)
You can now take a stab at it.
Here’s another example of "transmutation"
How long does it take me type 5,000 words?
No idea?
Me neither!
What if I tell you that I can type 50 words per minute?
(I can’t type anything like that fast… but it keep the maths easy)
5000 words, 50 words per minute.
100 minutes.
Words transmuted into time.
We're talked about DISTANCE... to TIME
WORDS… to TIME
Wouldn't it be useful if there was something like these
that we could apply to software development.
Something that we could measure easily and transmute into TIME
Trouble is.
The things in software that are easy to measure
have some drawbacks
It's easy to measure
Number of lines of code
Number of functions
Number of commits into source control
All easy to measure
These turn out to be bad choices:
Measure lines of code…
and you get lots of useless lines of code.
Measure number the functions… and you get lots of useless functions
Measure commits…
and you get lots of meaningless commits.
In any case, these things all depend on coding
- and coding comes a little late in the process.
We want something that could be applied in the planning phase.
Enter the star of today’s show: the Story Point.
The Story Points are used to indicate the “size” of
a Story.
Or Feature.
Or task.
Or piece of work.
Story points share some of the properties
of the “transmutable” things we looked at earlier.
If one particular Feature is 5 Story Points in size
We can each apply our own "transmutation"
I might think that I could complete it in 5 days.
A more gifted colleague might think that she could
complete it in 4 days.
So far so good..
And now we hit a bump in the road.
Miles….
kilometres…They are well-defined.
They are concrete.
We’re unlikely to argue about the size of a mile.
When we talk about miles (or kilometres) we both know what we're talking about
Miles - kilometres - are concrete concepts.
A Story Point is an abstract concept.
There’s nowhere you can go to look up the size of a Story Point
As it turns out, that’s not as big a problem as it might seem at first sight.
I’ll tell you why at the beginning of the next episode.
Thank you very much for watching
If you enjoyed this episode,
Please click to like
Share it with your network
And hit the logo
For a new episode every Wednesday.