Karmona Pragmatic Blog

Underestimation is Underestimated (a.k.a. Overestimation is Overestimated)

Sometimes it seems like we have an underestimation gene embedded really deep in our cognition but for some “obvious” reason (e.g. underestimation! :) most manager will rather “fight” overestimation and *not* underestimation.

Disclaimer: I have originally estimated this post will take ~33 min but it took me ~240% more time… (this is why I prefer to tweet lately ;)

Six annoying facts about our (/homo sapiens) planning or estimation “skills”:

• We are basically optimistic and have strong desire to please
• We tend to have incomplete recall of previous experience
• We tend to have focus bias when estimating e.g. estimating only the coding phase estimations which is only ~14-37% of the required work
• We tend to postpone what we can a.k.a. “The Student Syndrome”  (Eliyahu M. Goldratt, Critical Chain)
• “It always takes longer than you expect, even when you take into account Hofstadter’s Law” (Douglas Hofstadter, Godel, Escher, Bach: An Eternal Golden Braid)
• We tend to underestimate task completion times – a.k.a. The planning fallacy

Overestimation is Overestimated

“The developers say that this project will take 6 months… I think there’s some padding in their estimates and some fat that can be squeezed out of them…we also need to instill a sense of urgency in the development team… so I’m going to insist on a 3-month schedule. I don’t really believe the project can be completed in 3 months, but that’s what I’m going to present to the developers. If I’m right, the developers might deliver in 4 or 5 months. Worst case, the developers will deliver in the 6 months they originally estimated” (Does this ring *any* bell???)

Four reasons on managers tendency to “fight” overestimations:

• Underestimation (see above :) | “The feature estimation seems bloated” | “Isn’t it 20 min work?” | “Just add another index to the %$^&ing table?” | “It is only one more button…”
• Unreasonable time constraint | “We need this feature yesterday” | “Nothing is impossible for the man who doesn’t have to do it himself” (A. H. Weiler)
• True belief that Parkinson’s “Law” is really a law – “Work expands so as to fill the time available for its completion”
• “The Student Syndrome”  (see above)

So… if feature estimation seems bloated, managers and other project stakeholders fear that Parkinson’s Law and the Student Syndrome would kick in and therefore consciously squeeze the estimates to try to control it (a.k.a. “The Parkinson’s Squeeze”) and when we squeeze where it isn’t needed or was squeezed already, it immediately lead to… UNDERESTIMATION (!!!)

Underestimation is Underestimated

Underestimation creates numerous problems – some obvious, some not so obvious.

• Reduced effectiveness of project plans – Low estimates undermine effective planning by feeding bad assumptions into plans for specific activities. They can cause planning errors in the team size, such as planning to use a team that’s smaller than it should be. They can undermine the ability to coordinate among groups – if the groups aren’t ready when they said they would be, other groups won’t be able to integrate with their work. If the estimation errors caused the plans to be off by only 5% or 10%, those errors wouldn’t cause any significant problems but numerous studies have found that software estimates are often inaccurate by 100% or more (see above). When the planning assumptions are wrong by this magnitude, the average project’s plans are based on assumptions that are so far off that the plans are virtually useless.
• Statistically reduced chance of on-time completion – Developers typically estimate 20% to 30% lower than their actual effort. Merely using their normal estimates makes the project plans optimistic. Reducing their estimates even further simply reduces the chances of on-time completion even more.
• Poor technical foundation leads to worse-than-nominal results. A low estimate can cause you to spend too little time on upstream activities such as requirements and design. If you don’t put enough focus on requirements and design, you’ll get to redo your requirements and redo your design later in the project – at greater cost than if you’d done those activities well in the first place. This ultimately makes your project take much longer than it would have taken with an accurate estimate.
• Destructive late-project dynamics make the project worse than nominal Once a project gets into “late” status, project teams engage in numerous activities that they don’t need to engage in during an “on-time” project… below are some examples when the important characteristic of each of these activities is that they don’t need to occur at all when a project is meeting its goals, these extra activities drain time away from productive work on the project and make it take longer than it would if it were estimated and planned accurately
  • More status meetings with upper management to discuss how to get the project back on track
  • Frequent re-estimation, late in the project, to determine just when the project will be completed.
  • Apologizing to key customers for missing delivery dates (including attending meetings with those customers).
  • Preparing interim releases to support customer demos, trade shows, and so on. If the software were ready on time, the software itself could be used, and no interim release would be necessary.
  • More discussions about which requirements absolutely must be added because the project has been underway so long.
  • Fixing problems arising from quick and dirty workarounds that were implemented earlier in response to the schedule pressure.

Tip of the day
Never intentionally underestimate. The penalty for underestimation is more severe than the penalty for overestimation. Address concerns about overestimation through control, tracking and *mentoring* but not by bias.

****************************************

More related posts (a.k.a. people who read this post also read these posts)

• Software projects anxiety
• The Stockdale Paradox the Pessimistic Developer paradigm
• In Broken Images
• The Dunning Kruger Effect
• The Cone of Uncertainty in Pastel

“The further a project progressed, the more accurate the estimates for the remaining effort and time became”
(Barry Boehm, “Software Engineering Economics“, 1981)
 
NASA also came to the same conclusion that in the beginning of the project life cycle (i.e. before gathering of requirements) estimations have in general an uncertainty of factor 4. This means that the actual duration can be 4 times or 1/4th of the first estimations…
 
I felt very free to add my own interpretation of the different point-of-views with cool pastel colors as a sneak-peak cool-beta-preview of my next post.

Make sense?
 

“The British merchant ship Madagascar set sail from Melbourne in August 1853, headed for London and carrying 60,000 ounces of gold dust. – She was never seen again…” (http://www.futilitycloset.com/2008/01/29/overdue/)

Well… Saying “no more gold dust” is the only way I know to close a software release on-time…

P.S. Did you noticed that the Mona Lisa has no eyebrows. (http://www.futilitycloset.com/2008/02/12/trivium-16/)

My rough estimation is that the number of software project managers in the world is smaller in (at least) one scale from the conceived time-estimation techniques and this post is my humble four-cents contribution on how to do pragmatic time estimation for software projects (just finished one in Delver).

• Start with the mother of all lists to store your Product Manager wish list– We use eScrum Product-Backlog to store our work-items
• Prioritized them – We use 0-Yesterday; 1-Must; 2-Important; 3-Nice-to-Have and 4-”Forget-About-It”… ;-)
• Get relative estimations on all items
  • Granularity is the bronze-bullet for time estimations – Strive to the finest grained possible in reasonable time-frame  e.g. We usually aim for 2-5 days granularity in 2-3 days of time-boxed-estimation-period since the finest granularity in planning without reasonable time-box might take twice the time of doing the planned work (a.k.a. The Estimation Paradox)
  • Experience can turn your bronze bullet into silver one (ye ye, a silver one) – Relative estimation is calculated relatively upon a common scale of known work items from the team history e.g. We use Scrum “Story Points” and constantly measure the team velocity for time estimation adjustments
  • Fibonacci sequence (0, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89 etc.) can be used to “embed” the complexity and risk of rough (with insufficient drilldown) estimations e.g. if your estimation granularity for specific task reach ~40 days then your pragmatic estimation should be around 55 days (= the closest Fibonacci sequence) since it is reasonable to believe your (insufficient) granularity conceals risk, complexity and unknowns issues which requires Fibonacci-like-”buffering”
  • Strive to synchronize your time estimation techniques into very simple one – different time estimation conventions in the same development team is the 2nd reason for time delays. (I will give 0.95$ grant if you can guess what the 1st reason)
  • I know I am different but personally, I do prefer to have “pragmatic hours” vs. the normal Agile “ideal hours” and to start the project when 1 “Story Point” =  1 “Pragmatic Day” so long everyone understand this will change as soon as you start the project and then you need to return to velocity tracking to calculate the end
  • Don’t be naïve (a.k.a. “Ideal  Days”) with two known flavors:
    • Optimistic time estimations,  assuming 24*7 of concentrated programming ability with no outside interference (a.k.a. no such thing)
    • “Stupid” hand-waiving time estimations a.k.a. It is only 10 min to code this (but ~5 days to Integrate, Review, Design, Test, Schema and DAL changes, I18N support, Styling etc.)
• Get the rough project estimation = Sum of all product backlog story points / 22 (work days in month) / Number of relevant people
  • Usually this calculation will show you don’t have enough time for the project (even without project dependencies buffer which can be added later)
  • Start the “Tradeoff Game” – Try to cut items (content) based on the relative ROI
  • Revalidate your priorities since they will be the main tool (beside dependencies) for creating the project work plan.

As I see it, estimating software projects in a realistic time-frame is a statistic prediction of chaotic, time-delay-series of events and will never be straightforward nor easy so you can only do your best in the estimation and then track the project as it goes and make the needed adaptation on the way upon crystal clear project priorities.

Good Luck!

* The 1st manned landing on Earth’s Moon was the Apollo 11 mission on July 20, 1969 and the last one was Apollo 17 on December 7, 1972
* Current U.S. Vision for Space Exploration calls for a human landing on the Moon no later than 2019

2019-1972=47 (!!!)

Someone wise once gave this as a metaphorical example for a common engineers disorder, he called experience-anxiety-disorder, claiming that NASA stopped sending manned missions to the moon since they now know much more about the complexity and risk with doing this.

During the early seventies, it was a nice, naive working implementation but when NASA engineers started thinking about the next release they have built a five-decades-project-plan simply because they considered all the technological experience they have gained into large complexity buffers.

The Moral Lesson
Keep-it-simple can-do-approach and don’t over-complicate things with the long-tail-little-details when not needed or the project will take 5 decades to finish.

How do you know you are have an experience-anxiety-disorder?
If someone ask you to add a button to change the database schema and this make you feel a mixture of fear, apprehension, heart palpitations, nausea, chest pain, shortness of breath and headache.

What to do?
Sit down and relax, drink a cup of water and then add the damn button!

Last Long-Tail-Detail
Well… I don’t want to ruin this lovely moral lesson with the long-tail-little-detail but the real facts behind this 47 years gap were politics and money (as always) and not that NASA engineers got a severe experience-anxiety-disorder.

Google Trends (a.k.a. my experiment – part IV – Almost forgot…)

• Betty Casey
  
• Most Haunted Life
  
• Piercing & Tattoos
  
• Madonna
  
• World War III (…)