A newer version of this slide-deck is available for free (CC-BY-SA) at https://goo.gl/YnyoG4 Importance of Effort Estimation and how to get it right. - 6 reasons why estimates tend to be wrong. - The 7th secret reason why estimates are wrong. - Cone of Uncertainty. - Estimates : the usual suspects. - How to avoid accidentally conveying confidence.

1. EFFORT ESTIMATION
Write down
the number of “squares”
in the above image…

2. 5 REASONS WHY ESTIMATES TEND TO BE WRONG
1. Ambiguous/Incomplete Requirements. No documented use-cases.
2. Using Assumptions/Gut-feeling. Instead of facts.
3. Large-Scale. No breakdown structure = Omitted activities.
4. Single-Point Estimates. Average ≠ Conditional.
5. Bad work processes Bad design, code  Bugs  Rework/Firefighting.

3. THE 6TH SECRET REASON WHY ESTIMATES ARE WRONG
OFF THE CUFF ESTIMATES !
Q. Can you get this done by Friday?
Answer: Looks do-able. I will try.
What is the right question? What is the right way to answer it?

4. CONE OF UNCERTAINTY

5. ¯_(ツ)_/¯ NOT KNOWING THE ANSWER IS OKAY

6. THE 6TH SECRET REASON WHY ESTIMATES ARE WRONG
1. Ambiguous/Incomplete Requirements. No documented use-cases.
2. Using Assumptions/Gut-feeling. Instead of facts.
3. Large-Scale. No breakdown structure = Omitted activities.
4. Single-Point Estimates. Average ≠ Conditional.
5. Bad work processes Bad design, code  Bugs  Rework/Firefighting.
5 REASONS
Q. Can you get this done by Friday?
Answer: Looks do-able. I will try.

7. RIGHT QUESTION? / RIGHT WAY TO ANSWER IT?
1. Ambiguous/Incomplete Requirements. No documented use-cases.
2. Using Assumptions/Gut-feeling. Instead of facts.
3. Large-Scale. No breakdown structure = Omitted activities.
4. Single-Point Estimates. Average ≠ Conditional.
5. Bad work processes Bad design, code  Bugs  Rework/Firefighting.
Q. Can you get this done by Friday?
Answer: Looks do-able. I will try.

8. ESTIMATES
THE USUAL SUSPECTS
Reference: Software Estimation
Demystifying the Black Art
– Steve McConnell

9. PRECISION = UNINTENDED CONFIDENCE.
It is10:30 am. You are on your way to meet a friend…
You: “Will see you at the mall by 11 o’clock.”
Sounds like will be there sometime before 11:05
VS.
You: “Will meet you at the mall at 10:58am.”
Sounds like will be there sometime before 10:59
The 2nd estimate was simply based on
an ETA of 28mins shown by the navigation app at 10:30.

10. INTERESTING BITS FROM AROUND THE WORLD...
Calculating Functions Points - A practical example…
 stackoverflow.com/q/34473698/319204
“Function Points? Valuable, but too much effort to get right.” - Mike Cohn (Scrum Alliance)
 stackoverflow.com/a/153458/319204
12 tips to better estimates
 stackoverflow.com/a/35571856/319204
PMBOK – 5th Edition
 A Guide to the Project Management Body of Knowledge – 5e