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Vishwadeep Khatri

Brooks's Law

Brooks's Law states that adding manpower or deploying resources to a delayed project will delay the project further instead of speeding it up. This law was proposed by Fred Brooks, a software engineer in his book - The Mythical Man-Month.


An application-oriented question on the topic along with responses can be seen below. The best answer was provided by Raj Saxena and Rajeshwari


Applause for all the respondents - Raj Saxena, Rajeshwari, Premkumar T, Tushar Maradwar


Q 269. Brooks's Law states that adding people to a delayed software project delays it further instead of making it faster. Explain whether and how Brooks's law applies to delayed Lean Six Sigma projects.



Note for website visitors - Two questions are asked every week on this platform. One on Tuesday and the other on Friday.

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Brook’s Law

Brook’s Law is: “Adding additional resources to a late software development project will make the project later”.


Q1. Whether Brook’s Law applies to delayed Lean Six Sigma Projects?

Answer: Yes it applies to Lean Six Sigma Projects.


Q2. How Brook’s Law applies to delayed Lean Six Sigma Projects?


Brook’s Law can also be applied to dissimilar types of Projects (could be challenging or methodological projects) where highly skilled and experienced workforce are required.

There are following reasons which tells how this Law applies.

a.       Adding new people in existing projects takes more time for them to become productive. And this what has been called “Ramp Up” time as per Brook’s law. The biggest concern of adding new people in existing running project is: it distract the resources who are already working on the project and this distraction results in productivity loss of old resources and at the same time new resources are not yet contributing.

Why existing resources becomes less productive?

1.       Existing resources are being used to educate the new added people.

2.       They have to spare their work so that training can be conducted for new resources.

3.       Temporary movement from existing work to training will stop the focus and work on running project.



b.  Communication overheads increases as the new resource added. Since everybody on this project needs to be in sync in order to make task aligned. So when new resources are added then more discussion, more meeting to be make everybody in sync and they spend more time to understand others work.




Brook’s Law in SIX SIGMA Project

If we talk about Brook’s Law in SIX sigma project typically in DMAIC approach the here is the answer.


Define & Measure Phase:

While Brook’s law doesn’t applies on early stage of project so it can be considered that if we add more people during the Define and Measures phase which is considered as early phase where we define problem statement and getting understand then Brook’s law may not be applies.




Analyze, Improve & Control Phases:

Let’s understand how it’s applied in these three phases,

-          Analyze - While working for analyzing and validating and selecting the root cause, one has to be aware with the data collection method along with Problem statement.

-          Improve - Adding people during improve phase will make project delays as in this phase team is already working on testing and implementation phase and new added people needs complete information about the validation and selection of root cause before understand the testing process.

-          Control – addition on new people in control phase will surely create some delay as existing resource will be distract to make new people understand the whole project.


Simulation of Project Delay & Brook’s Law: -

-          Project Starts: Planned to Complete in 12 months

-          Month 10: Project manager proposed to add two new resources in the existing project for targeting to complete this project in 12 Months Whereas Engineers has said that they have already completed 70% of Project and 30% of Project will be completed in next two months.

-          Month 11: Team has informed that it can’t be completed in month 12 as per commitment. Discussion started on Brook’s law and Project manager added two new resources and postpone to complete this project in 13 months.

-          Month 13: Project is not yet ready and Engineers recalled to Project Manager for violating Brook’s law of adding new people.

Month 14: Project is ready and released late by 2 months.



Co-relates why Simulated Project delayed and How Brook’s Law applies: -

-          Educating New added resources: - Existing/experience (Or Best known project people) resources are being use to educate new resource which distract them from the running project work and consume their work in training work. This makes them less productivity thus its resulting in Project delay. Example – if we explain above simulation, you will see that project was 1 month delay and to cover this 1 month, project manager added two new resources and violated the Brook’s Law. In this case, when existing resources started focusing on education of new people then they would be requiring more time to complete their work and this explains why the project is delayed more.

-          Multiple Communication: - To make a good and successful project the communication is key and keeping every individual in sync is important. Since new resource have been added in project then more communication require to keep them in sync and also to keep watch on what every individual is doing. This requires ample time to make everybody aware with project details and keep in sync which justify the fact of delaying the project as it distracts the existing resources.


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Brook's law was coined by Fred Books. It is a claim about the software project management that adding more manpower/resources to a software project makes it even more delayed.This can be applied for Six Sigma projects as well.

  • Ideally when ever we have an additional resource added at the later stage there is a ramp up time where the resource takes time to onboard and understand the sequence of activities that has been carried out for long period and ideally six sigma projects are for a longer duration, there would also be a struggle if there is no domain knowledge because there is a struggle in understanding the progress and also understanding the business nuances. 
  • The new added team members also would need to integrate to multiple people who were involved in the project to understand the same end to end.
  • It is also very important that the tasks are divided appropriately, if the same task is done by different people, substantial time and effort is spent on understanding what the other team members are working
  • There is also lot ambiguity since there is an increase in number of communications
  • There would be tasks that cannot be divided and would need longer duration in which case adding additional people would not help
  • In case the project is complex and involves synergies between cross functional teams then it could get tough to manage the timelines
  • There is often a variance in the plan vs what we execute since some of the projects might have more outliers or would need additional analysis or deepdive which we don't foresee when we begin the project
  • Brooks law ideally applies to adding people late in the project however if we have people on- boarded in the beginning of the project with the right skillset to understand from domain perspective  that would be helpful.
  • Project plan also should be relooked in case of delays if it is due to an incorrect estimate of the task, in that case correction of the plan is the best way


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Brooks's law is an observation about software project management according to which "adding manpower to a late software project makes it later" It was first termed by Fred Brooks in his 1975 book The Mythical Man-Month. According to Brooks, there is an incremental person who, when added to a project, makes it take more, not less time.


Brooks’s law, working principle:


Ø Adding an unskilled or untrained member in an already project will lead to project delay further due to training and new problem because of unskilled/untrained


Ø If overhead increases in a project, the time taken for communication for synchronising team will increase further leads to project delay


Ø In case of a complex task, not possible to divide as workable tasks.  Even you divided it will create more chaos which results in project in other way specific tasks takes its own lead time due to technological limit even adding manpower will not support in reducing lead time




Ø Its only applicable on ALREADY LATE PROJECT, not for all other situations


Ø If specialist added during the RAMP UP (Project at delayed stage) period, it will not affect by Brooks law


Ø Due to modern practices such as Continuous Integration will take care of communication at any such situation


Ø A precise Design Pattern will simplify the distribution of work



Application on Lean Six Sigma Project:


Ø Based on Brooks Law its understood that a clear frame work to be defined at start of project to avoid the delays due to adding a new man power in the project team.  A clear frame work help in setting roles & responsibilities therefore if any member left the project team its now ease to take a decision which Subject Matter Expert required as a replacement in the team to complete the project on time.


Ø Advantage of digital to be considered, for bringing the team in a focused way instead confusion due to communication within the team


Ø The Cons in line to Brooks law for a Lean six sigma project:


-         Complex tasks will be completed by its own time, further adding man power at Ramp up stage will not help


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 Brook’s law was developed by Fred Brooks in 1975 in his book “The Mythical Man-Month” . It is for Software project Management, according to this  when a person is added to a project team, and the project is already late, the project time is longer rather than shorter.


Explain whether and how Brook's law applies to delayed Lean Six Sigma projects.

In Lean Six sigma projects, DMAIC is structured and  systematic approach , where Project team get form in Define phase. each member in Team has unique roles and responsibilities following are key roles in any Lean six sigma projects- Champion, Master black Belt,  Green belt, Team member, Process owner, Project sponsor. Team in lean six sigma project get selected based on their knowledge about the process which need to improve and understanding on the basic concepts of Lean Six Sigma, so this is prerequisite for Team members.


Brook’s law also get applies for delayed Lean Six sigma project , here adding people will not be able to brought back project in control , because new Team members initially will be in “RAMP UP” phase , in this phase they will take some time to become productive and for it, they need to get aware about Business case of project , should have Knowledge about process which need to improve and know how on Lean Six Sigma. To do this existing Senior member will get engaged to train new Team members which result in slow the speed of project further more.

Adding people in delayed Lean Six sigma project will not be able to add value from day one because they have to go from 4 phases of Team development (i.e. Forming, Storming, Norming and Performing ) with existing Team members, it will take some time so project delay further instead of making it faster.


As per Brook’s law communication overhead increases as the number of people increases same get applies in delayed Lean Six Sigma project so we should not appoint more people in a Lean Six Sigma team because adding a large team will be ineffective since the responsibilities are diluted and it is more difficult to reach a consensus and at last it will increase number of communication channel.


As in Lean Six Sigma project specialties required in terms of Tools/technique like knowledge on Process , Project charter, VSM, SIPOC, FMEA, Control charts etc so highly divisible tasks are less , so directly adding people will not speed up project, until unless new people get add with required capability.

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