Agile Principle #8: Enough Is Enough!
by Kelly Waters
Pareto's law is more commonly known as the 80/20 rule. The theory is about the law of distribution and how many things have a similar distribution curve. This means that *typically* 80% of your results may actually come from only 20% of your efforts!Pareto's law can be seen in many situations - not literally 80/20 but certainly the principle that the majority of your results will often come from the minority of your efforts.
So the really smart people are the people who can see (up-front without the benefit of hind-sight) *which* 20% to focus on. In agile development, we should try to apply the 80/20 rule, seeking to focus on the important 20% of effort that gets the majority of the results.
If the quality of your application isn't life-threatening, if you have control over the scope, and if speed-to-market is of primary importance, why not seek to deliver the important 80% of your product in just 20% of the time? In fact, in that particular scenario, you could ask why you would ever bother doing the last 20%?
Now that doesn't mean your product should be fundamentally flawed, a bad user experience, or full of faults. It just means that developing some features, or the richness of some features, is going the extra mile and has a diminishing return that may not be worthwhile.
So does that statement conflict with my other recent post: "done means DONE!"? Not really. Because within each Sprint or iteration, what you *do* choose to develop *does* need to be 100% complete within the iteration.
As a slight aside, I was at Microsoft last week for an executive briefing on all their latest products. Sharepoint 2007 looks great by the way; a real leap from the earlier versions which were not really up to scratch. Vista, for those that haven't tried it, looked rather slow even on a laptop with 4GB RAM! And apart from being slightly prettier didn't really seem to offer much. Windows Workflow Services and .Net v3 looked pretty cool, if you can afford to develop in Microsoft tools ;-)
Anyway, back to my point about the 80/20 rule, Microsoft's own research found that the average user of Word uses only *8%* of the functionality. That's 8%! And I wouldn't mind betting at least 80% of us use the same 8% too! [assertion]. If Microsoft had developed only the important 8% of Word, maybe they could still have captured the same market share? Maybe, maybe not; sadly we will never know.
It's also worth considering the impact on user experience. Google has shown us that users often prefer apps that do just what you want. That's *just* what you want. And no more. The rest is arguably clutter and actually interferes with the user experience for only a limited benefit to a limited set of users.
So in an agile development world, when you're developing a brand new product, think very hard about what your app is *really* all about. Could you take it to market with all the important features, or with features that are less functionally rich, in a fraction of the time?
Apart from reduced cost, reduced risk and higher benefits by being quicker to market, you also get to build on the first release of the product based on real customer feedback.
So all of this is really common sense I suppose. But it's amazing how often development teams, with all the right intentions, over-engineer their solution. Either technically, or functionally, or both.
The really tough question, however, is can you see up-front *which* 20% is the important 20%? - the 20% that will deliver 80% of the results. In very many cases, the answer sadly is no.
As a slight aside, I was at Microsoft last week for an executive briefing on all their latest products. Sharepoint 2007 looks great by the way; a real leap from the earlier versions which were not really up to scratch. Vista, for those that haven't tried it, looked rather slow even on a laptop with 4GB RAM! And apart from being slightly prettier didn't really seem to offer much. Windows Workflow Services and .Net v3 looked pretty cool, if you can afford to develop in Microsoft tools ;-)
Anyway, back to my point about the 80/20 rule, Microsoft's own research found that the average user of Word uses only *8%* of the functionality. That's 8%! And I wouldn't mind betting at least 80% of us use the same 8% too! [assertion]. If Microsoft had developed only the important 8% of Word, maybe they could still have captured the same market share? Maybe, maybe not; sadly we will never know.
It's also worth considering the impact on user experience. Google has shown us that users often prefer apps that do just what you want. That's *just* what you want. And no more. The rest is arguably clutter and actually interferes with the user experience for only a limited benefit to a limited set of users.
So in an agile development world, when you're developing a brand new product, think very hard about what your app is *really* all about. Could you take it to market with all the important features, or with features that are less functionally rich, in a fraction of the time?
Apart from reduced cost, reduced risk and higher benefits by being quicker to market, you also get to build on the first release of the product based on real customer feedback.
So all of this is really common sense I suppose. But it's amazing how often development teams, with all the right intentions, over-engineer their solution. Either technically, or functionally, or both.
The really tough question, however, is can you see up-front *which* 20% is the important 20%? - the 20% that will deliver 80% of the results. In very many cases, the answer sadly is no.
For more agile principles, see 10 Key Principles of Agile Software Development
2 May 2007 19:02
The 80/20 rule is one often applied in leadership and management development and is therefore likely to be a concept that can be rolled out to customers in a manner in which they feel confident.
It is also interesting to consider the useability of developed software from a user perspective - if I am never going to use a specific piece of functionality then it's requirement is questionable.
In cases where software is designed in a manner that will allow increased or even altered functionality in the future, ensuring that users are enthusiastic and comfortable with common tasks during early iterations builds trust and confidence in the development. This often results in increased user participation, better feedback and ultimatley and cleaner and better solution.
So all in all, I agree, the Pareto principle can be a powerful tool for organising iterations, and also communicating those to the client and end user.
13 May 2007 03:52
Great post!
I suggest that you don't have to know up front what that 20% is right out of the gate. Even if you just guess what it is, that's probably good enough. Once you have that 20% to show, you'll get the user feedback that will help you make an even better guess in the next release. Plus, if you can't guess what that 20% is, perhaps you are in the wrong market or need to spend more time learning about your market!
23 July 2007 22:06
Well, it seems to me that one could know 80% of the 80% that needs to be done up front, by doing 20% of the research you'd have to do to get the other 20%.
And so on....
29 April 2008 15:52
This is a fine concept on paper, yet I rarely find real world examples in which demonstrate HOW you save 80% of the time. In every project I've worked on (software project that is), it's not the case that 80% of the requested features can easily be split out and delivered in short order. The 80/20 rule actually ends up meaning "80% of the code is easy to write, given a reasonable architectural and design pass was done. But there is the final 20%, required in order to get the application to actually boot, run, stay running, and have a modicum of performance". This has always been the case regardless of how much I minimize scope to get things out the door faster. 80% bang for 20% effort does NOT logically imply that you can get away with not doing the 20%, unless you are writing vapor ware, proof of concepts, or college projects.
14 August 2008 03:15
Well, maybe you are just using the principle with the wrong fact. I mean, why not develop 20 % of the features that add 80 % of the software value.
This approach can be hold on what Poppendieck reports on their "Lean Software Development". They say that a Standish Group study found that 45% of software features are never used and 19% are rarely used. So, 64% of the features you implemented in the software does not aggregate no value to the product. SO, how many that could you have saved focusing on what really adds value to the product.
9 September 2008 09:09
Well, and I always thought that implementing 90% of the features take up 90% of the time - and the other 10% require the other 90% of the time.
I guess I should try out this "agile" thing, if that brings that down to 80% :-)
(Thanks for the nice article, btw. :-)
24 March 2009 00:12
As a mathematician, I feel obligated to point out that almost everyone misunderstands the nature of statistical laws. Awareness of the truth of an inescapable trend does not mean you can escape the trend!
You will still most likely spend 80% of your effort on what you consider to be only 20% of the difficulty, even if you keep trying to avoid the perceived over-concentration of effort.
Therefore avoiding unwanted features has nothing to do with the real, original 80/20 rule. Neither does the idea of rapid rollout and later stabilization.
There is no 80% of the work that can be saved or reallocated by finding some pernicious 20% of the problem space -- that way lie the dragons of analysis paralysis and heavy protocol.
Pareto's is a law of a statistical nature, not an observation of human decision-making processes. So we need to work with the truth instead of against it. As work draws time and its requirements just won't settle down, don't resent it or take it personally. The perceived disparity of returns is preordained, and will average out to 4-to-1, whatever you do. (And that is lovely, because it is true. Plato's God says so.)
So detach from it. Do not be led to consider unexpectedly hard work more important, or less. Do not give it more scrutiny and criticism, or less.
Do not declare war on it or dig in to discover the cause of this perversity. Doing so is exactly the kind of reflexive over-analysis to which agile technologies are meant to be an anodyne.
1 December 2009 09:12
Thanks for the fantastic article! The Pareto's principle should be undoubtedly taken into consideration when developing software, because we are catering for the end user in fact. It would be great if all the clients understood it.
4 May 2010 10:40
I only read 20% of the article. I guess I got 80% of the content that way.