Talk:Ninety–ninety rule

Shouldn't this say the first 90% takes 10% of time, the remaining 10% takes 90% of time? Or are we saying a program takes 180% of predicted time to write? --rmhermen
 * The quote is accurate, which is what we are reporting here :-). Pete 00:42, 19 Sep 2003 (UTC)


 * Someone has "fixed" the quote. I have added back the humorous version which is found in Murphy's law type compendiums. Ellsworth 00:09, 9 September 2005 (UTC)

But the "180% of time" is the gag of the whole rule!!! It wants to make clear that people often make big mistakes while predicting the time needed for the implementation of the code. --Jochen


 * Yes, you are exactly right. Looking at the history of the article, it is clear that an anonymous user (IP 83.149.32.48) made the mistake of thinking that the quote was a typo. He then made an edit on June 18, 2005 to correct the "typo". (And ironically his edit summary had a typo.) But if you look at the actual source of the Tom Cargill's quote, you will see that the "180% time" variation is indeed Cargill's original version, not some variant. Vocaro 07:13, 6 September 2006 (UTC)


 * I have edited the page so that Cargill's original quote appears properly. Vocaro 07:47, 6 September 2006 (UTC)

problem
the quote and the 'corrected' quote are the same Brainhell 04:08, 17 December 2006 (UTC)
 * Not quite, the difference is bolded:


 * "The first 90% of the code accounts for the first 10%/90% of the development time. The remaining 10% of the code accounts for the other 90% of the development time."


 * –Adrian J. Hunter 05:49, 11 January 2007 (UTC)

This quote is actually slightly incorrect. Having 180% of the time is important for the chuckle, but the code should only add up to 100%, not 90/90 as well. —Preceding unsigned comment added by 70.164.72.231 (talk) 16:07, 23 January 2009 (UTC)

alternative rule
While looking for the rule by its name, I found another variant here: http://obvious.services.net/2011/06/90-90-rule-of-project-management.html
 * The 90 - 90 rule of project management
 * The first 90% of the work takes the first 90% of the time.
 * Then, the other 90% of the work takes the other 90% of the time.

I also thought it was a typo, at first (both parts add up to 180%). Then I thought that it emphasises how not only the "raw" time to complete the work, but as well any other quantitative measurement of work (i.e. materials, effort, expected lines of code) can be underestimated when making projections. In this interpretation, I think the "formula" and its sarcasm are valid in their own right.
 * -[Jim Klimov] 18:39, 13 January 2012 (MSD) — Preceding unsigned comment added by 81.5.113.11 (talk)

Removed section
I removed the section called 'Prior art', which described a supposed previous version of this rule. Anecdotes of the 'I knew a guy once...' kind are not sufficiently verifiable or notable to be included on Wikipedia. Terraxos 03:46, 19 July 2007 (UTC)

Mistaken for a "typo" ?
Typo? Or mis-spelling

Deleted "humorous fact"
Programmer's dream is to identify... (etc.) - I think this kind of "facts" should not be in a place like wikipedia.

Alternative
I've always heard this as "90% complete, 90% of the time", meaning that it takes the longest time during a development to do the seemingly small things at the end of the development. And that this is certainly not only in software circles, but most any development of any kind. Should this be added to the article? 202.78.155.23 (talk) 05:00, 9 July 2008 (UTC)


 * Frankly, no. The article is about a particular humorous but on-target aphorism. Your personal observation, however much it make you happy to know it might be true, belongs in your personal blog or web page. Snezzy (talk) 23:14, 22 July 2008 (UTC)

Original
If you look at the original paper this is referred to as the "Rule of Credibility"

&lt;quote&gt; [Rule of Credibility] The first 90 percent of the code accounts for the first 90 percent of the development time. The remaining 10 percent of the code accounts for the other 90 percent of the development time.

Tom Cargill Belt Labs &lt;/quote&gt;--myork (talk) 21:58, 27 January 2011 (UTC)


 * It's annoying the original is no longer freely available. I integrated your edit into the last paragraph. Adrian J. Hunter(talk•contribs) 12:08, 28 January 2011 (UTC)

Aphorism is not exclusive to computer programming and software development
While it may be true that the the aphorism with that specific wording is exclusive to the field of computer programming and software engineering it appears that the term "Ninety-Ninety Rule" and the general message behind the aphorism is not exclusive to these fields. Nowhere in the article does it explain where the name for the aphorism came from. None of the quotes in the article nor in the Talk Page contain the phrase "ninety-ninety." In fact, the only name given to the rule in the quotes is the "Rule of Credibility." Is there documentation for when the "Rule of Credibility" became "the Ninety-Ninety Rule"?

An online search for "ninety-ninety rule" turns up the following aphorism, attributed to Arthur Bloch, the writer of the Murphy's Law books.


 * "Ninety-Ninety Rule of Project Schedules: The first ninety percent of the task takes ninety percent of the time, and the last ten percent takes the other ninety percent."

This version of the aphorism is used in many fields.

I seem to recall that this was in the second of the Murphy's Law books, Murphy's Law Book Two: More Reasons Why Things Go Wrong!, which was published in January of 1980. I will have to look it up to be sure.

I can't tell when Tom Cargill made the statement/aphorism. There is a link in the Talk Page posted by user myork to the "original paper," but I received an error message when I tried it:


 * An error occurred while processing your request.
 * Reference #50.2e080f17.1446823711.63b4f197

If by the original document you mean Bentley's article, that appears here:

http://www.bowdoin.edu/~ltoma/teaching/cs340/spring05/coursestuff/Bentley_BumperSticker.pdf

So, what is the date of the use of the aphorism by Tom Cargill? We know it's sometime before the September 1985 publication of John Bentley's article. Bentley's article doesn't give a date. According to a biography on a page for Consulting Inc., his date of graduation is 1979. He began working at Bell Labs in 1982 and began work on C++ in 1983.

So, I'll look up the Murphy's law issue if someone with more knowledge of the computer world can find out earliest date of use by Cargill and when it became known as the ninety-ninety rule.

By the way, there's no Wikipedia article on Tom Cargill. Should there be one? Ileanadu (talk) 15:53, 6 November 2015 (UTC)

Citation to Bentley's article
It appears that "Programming Pearls" was a recurring title used by Bentley. For example:

Programming pearls: a literate program (June 1986)

Programming pearls: a spelling checker (May 1985)

Programming pearls: associative arrays (June 1985)

Thus, it might be useful to add the subtitle to that particular article. In this case, it's "Programming Pearls: Bumper-Sticker Computer Science. Ileanadu (talk) 15:56, 6 November 2015 (UTC)

Adds up to how much? (180 or 900?)
I'd rather "add it up" to 900 than to 180.

The way I understand it is that after reaching point p you expect to having finished 90% of your work.

When having actually finished you realize that 90% of the actual work was still left at point p (so you actually only finished 10% of all your work at point p).

So altogether you needed 900 of what you mistakenly considered being one percent at point p. -- 5.146.199.7 (talk) 19:34, 21 August 2017 (UTC)