Probabilistic Predictions

@SINGHPR - THEAGILEROUNDUP.COM

Probabilistic
Predictions
PRATEEK SINGH
@SINGHPR

Things We Will Not Talk About*
Scrum
Kanban
XP
Velocity
Stand Ups and Retrospectives
Continuous Integration/Continuous Delivery
Anything that is traditionally considered “Agile”
*Unless there is a direct question about it.

Things We Will Talk About
Weather, hurricanes in particular
Commuting to work
Led Zeppelin
Football
Elections (…and you thought you were done with that)
And if all that is not scary enough, we will be rolling dice…

Probabilistic World View
These examples will (hopefully) show that our world is not
deterministic.
Once we agree on the probabilistic nature of the world, we will try
to tackle the problem of making predictions.
Is my wife going to buy at least one thing from Amazon today?
(70% Yes)
If I played a random Led Zeppelin Song, How long will it last?

Commuting To Work1

Commuting To Work
13 Minutes

14 20%
19 50%
22 70%
24 85%
4/25/2017 5/15/2017 5/25/2017

"All My Love", 5:53
"Gallows Pole", 4:57
"In My Time of Dying", 11:08
"LA Drone" (instrumental), 0:14
"Stairway to Heaven", 8:02
0:00
1:12
2:24
3:36
4:48
6:00
7:12
8:24
9:36
10:48
12:00
0 20 40 60 80 100 120
Led Zeppelin (Avg = 5:07)
85%6:27
50%4:42
95%9:12

All That Is Well And Good But…
We are often asked to predict multiple items.
My feature/project/product is made up of 10-100 work items.
When will that be done?
How many work-items/stories/tasks can I get done in the next
month?

Is This Where We Talk About Football?

Date Touchdowns
9/11/2016 3
9/18/2016 2
9/25/2016 4
10/9/2016 2
10/16/2016 1
10/20/2016 3
10/30/2016 4
11/6/2016 3
11/13/2016 3
11/20/2016 3
11/28/2016 3
12/4/2016 3
12/11/2016 5
12/18/2016 3
12/24/2016 5
1/1/2017 4
Date Touchdowns
9/13/2015 4
9/20/2015 2
9/28/2015 5
10/4/2015 2
10/11/2015 3
10/18/2015 3
11/1/2015 1
11/8/2015 4
11/15/2015 2
11/22/2015 2
11/26/2015 1
12/3/2015 4
12/13/2015 4
12/20/2015 3
12/27/2015 1
1/3/2016 1

Average Per Game = 2.9
Number Of Games in a Season = 16
Prediction (2.91 * 16) = 47 (46.56)
How Many Touchdowns Next Season?

Flaw Of Averages
Plans based on average fail on average
A single number is one of many outcomes
Prediction -> Range & Probability
How confident are you in your forecast?

I II III IV V VI
I 3 4 5 2 3 1
II 2 3 3 4 3 4
III 4 3 5 4 1 4
IV 2 3 4 2 4 3
V 1 3 5 5 2 1
VI 3 3 1 2 2 1

Monte Carlo Exercise
Assign one dice to the horizontal and the other to the vertical axis.
Roll and note down the result from the grid.
Repeat for 16 rolls (1 for each game in the season)
Sum up the 16 results from the grid to get the prediction.
Enter Your result here –
http://tinyurl.com/MusicCityTDs

1 1
4 4 3
11 12
18
20
31
48
50
60
68
66
85
99
72
81
62
56
43
38
23
16
5
14
4 3
0 1 0 131 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63
Touchdowns
95% 50%80% 10%

Predicting Hurricanes

#covefe

Predicting The Election

If you track nothing else, track
the date that an item starts
and the date that an item
completes
(for all work items)

Communicate your
forecasts in terms of a
range and a probability

Update your forecasts as
you get more information
And
Favour short term forecasts
over long term forecasts

Most importantly:
The best forecasts in
the world are useless
unless you take
action

Further Reading
www.TheAgileRoundUp.com
https://www.infoq.com/articles/kanban-scaling-agile-ultimate
https://leanpub.com/whenwillitbedone

Thank You!

Probabilistic Predictions

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