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Thursday, May 16, 2013

13. The Mythical Man-Month - Part 2

As mentioned in the previous post, I plan on discussing some of my favorite chapters from The Mythical Man-Month.   What better place to start the Chapter 2 - The Mythical Man-Month!

To start with it is important to recognize four types of tasks:

  1. Perfectly partionable task
  2. Unpartionable task
  3. Partionable task requiring communication
  4. Partionable task requiring complex interaction
For type 1, adding people to the task will always reduce the elapsed time.  While not realistic for most project work, the model is clear.

For type 2, adding people to the task has no impact on the elapsed time.  The stereotypical example is it takes one woman nine months to have a baby - adding more women does not reduce the time!

For type 3, adding people to the task helps reduce the elapsed time, but the burden of communication increases as people are added so the benefit diminishes with each additional person.

For type 4, there comes a point where adding more people increase the elapsed time!  When Professor Brooks wrote this there were not robust collaboration tools available.  Those tools and better processes probably push the inflection point further, but it still exists.

The net result is Brook's Law:  

         Adding manpower to a late software project makes it later!  

The key learning is good project and resource planning.  The project manager needs to know where additional resources will help and where they will hurt.

Chapter 3 - The Surgical Team describes the criticality of role assignment.  Studies have consistently shown order of magnitude productivity differences between individuals.  Having the right people doing the right tasks is a second key.  

Chapter 4 - Aristocracy, Democracy, and System Design covers what we would probably now call System Architecture.   Put another way, design by committee is rarely a good thing - in buildings or in applications.  Professor Brook's key point is the necessity of Conceptual Integrity.

Next week I will cover some more chapters.  My hope is that these brief comments will make you want to read the entire book

  

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