Brooks’ Law

Brooks’ Law

I was looking for something on the SEI website and came across a piece about Brooks’ Law that caught my attention.  Brooks’ law is a principle in software development which says that “adding manpower to a late software project makes it later”. It was coined by Frederick P. Brooks, Jr. in his 1975 book The Mythical Man-Month.  You may have already experienced it but never put a name to it.

I would fall under that category.  I’ve seen Brooks’ Law happen first hand but didn’t know it had a name.

The vendor was doing predictive versus adaptive planning.  They did a very poor job of estimating.  Since the customer accepted the estimate, it was just a matter of time that the house of cards would come crashing down.  As time progressed through the period of performance, we saw the vendor reach each milestone later and later. (They were following a waterfall approach)  At each status meeting the vendor was pressed for an answer to the question of how they were going to recover the schedule.   When it was painfully clear that the vendor could not complete the scope of work (within the alloted time), even if they convinced their people to work nights and weekends, they proposed to bring on more people to take care of the backlog of work.  That’s right, they were going to bring on a small army with no experience with the customer, the program, or the product.  They were going to blow the budget, in the hopes to recover the schedule on the currently agreed upon scope of work.

One stakeholder was very candid when he said, during a status review

It sounds like the plan is to throw as much [something] at the wall as you can and see what sticks.

It’s rather sad that the vendor looked at this as such a simple equation.

Team A (Input) + Team B (Input) = Team A + Team B (Output)

In reality, the equation looked more like this:

Team A (Input) + Team B (Input) = [(Team A * .75) + (Team B * .50)] Output

Have you seen Brooks’ Law on your project?  What was the outcome?


2 Replies to “Brooks’ Law”

  1. If you haven’t read “The Mythical Man-Month,” I recommend it highly. Fred offers the example of picking cotton: if you double the number of folks picking cotton in a field, they’ll finish in (roughly) half the time, because they don’t need to communicate or coordinate, as they are each working in isolation on a highly repetitive task that requires little skill. Software development has none of these characteristics. The 20th anniversary edition added a lot of material.

    1. Though I have not read the book, it was reassuring to discover it existed. It’s amazing a book like this, that was published 20 years ago, it’s more widely understood or distributed.

      “What you know you can’t explain, but you feel it. You’ve felt it your entire life, that there’s something wrong with the world. You don’t know what it is, but it’s there, like a splinter in your mind, driving you mad.” – Morpheus (The Matrix)

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