Under what circumstances - if any - does adding programmers to a team actually speed development of an already late project?

+35  A: 

See The Mythical Man-Month

@edg: noob trying his hand (successfully) at rep-whoring. This too shall pass.
Christopher Mahan
@Christopher Mahan: No, I am not and frankly I find the accusation offensive. Why rehash a subject that Brooks handled so very well?
@Christopher Mahan: It's people like you that kill communities with your rude, unnecessary snarky attitude that everyone who doesn't expound for pages and pages is an idiot.
docgnome, I suggest you come up with a good (even bulletpointed) synopsis of the cases pointed out in TMMM that answers the question. Page numbers or at least chapters would be nice too. :)
Jon Limjap
We all lose when people leave brain-dead comments like the first one.
With a question like that, one would think the asker very likely *has already seen* the book, so simply mentioning its name does not add especially much.
docgnome, I actually thought it was a snarky "RTFM" type of response, (and rated up your comment to C.M. where you say snarky attitudes are unnecessary and kill communities). The reason that I thought that was that you were being snarky was it seemed like the OP already knew of the book, and was asking a specific question about our experience with one nuance before he went off to actually read it. As little as accusations of 'rep-whoring' and name calling are needed, differing to an outside source, in a discussion-ending way, stifles interest on possibly interesting topics.
+10  A: 

If the existing programmers are totally incompetent, then adding competent programmers may help.

I can imagine a situation where you had a very modular system, and the existing programmer(s) hadn't even started on a very isolated module. In that case, assigning just that portion of the project to a new programmer might help.

Basically the Mythical Man Month references are correct, except in contrived cases like the one I made up. Mr. Brooks did solid research to demonstrate that the networking and communication costs of adding new programmers to a project will outweigh any benefits you gain from their productivity.

Not really... still there is a cost of learning the code base alone... and if they are totally incompetent, the project will probably fail anyways.
Mike Stone
I agree with Mike Stone here. The code base and architecture could be flawed, 2-4 months ramp up time per developer for a serious project, all sorts of issues regarding technical leadership, etc. Ught...I get the willies thinking about it.
Stu Thompson
+65  A: 

The Mythical Man Month goes into great detail on this... adding people to a late project will not help... you have costs associated in bringing someone up to speed and them learning the code base that you just can't avoid. If the project is late, you will have to look to other ways to make it on time... such as cutting features that aren't really necessary.

Mike Stone
And like all truisms, it's sometimes wrong. As Brooks himself said in the Mythical Man Month, the law is an "outrageous oversimplification".
Airsource Ltd
The question asked "Under what circumstances - if any - does adding programmers to a team actually speed development of an already late project?", so an answer that answers the opposite is the accepted answer?
Windows programmer
@Windows Programmer, Sure, if the answer helps illustrate that there aren't any.. why not?
+1 for mentioning "Mythical Man Month", as it is covered exactly there.
+1  A: 

Found this, thought it might be useful:

Abyss Knight

When your critical path of building the program isn't a single line, but rather a series or paths. Then you can assign a programmer to each critical path.

textbook project management answer, one I've never witnessed
Ed Guiness
LOL, yeah... Sam... I think you need to read The Mythical Man-Month more than anyone :-) (it's a fun read anyways)
Mike Stone
agreed. another hopelessly romantic answer :P
Stu Thompson
I like my rose colored glasses, thank you very much. :-)

Potentially as a co-pilot. Think extreme programming pair method, but with out the experience from having the coding from start. This is assuming your co-pilot is familiar with any frame works you are using.

(just a guess though ^_~ )

your guess is as good as most i reckon
Ed Guiness
This is actually a pretty good idea.
+2  A: 
  • Self-contained modules that have yet to be started
  • Lacking development tools they can integrate (like an automated build manager)

Primarily I'm thinking of things that let them stay out of the currently developing people's way. I do agree with Mythical Man-Month, but I also think there are exceptions to everything.

Tom Ritter

When the work can be split into independent units and there are more such units than programmers already on the project.


If the architecture of the system being built allows for the modular addition of the remaining functionality, then adding extra programmers could actually get to the end faster. You'd need a very solid foundation and infrastructure, with plenty of excellent examples and documentation, to make this feasible. As we all know, this is pretty unlikely (but not impossible).

Jason Etheridge
+16  A: 

Maybe if the following conditions apply:

  1. The new programmers already understand the project and don't need any ramp-up time.
  2. The new programmers already are proficient with the development environment.
  3. No adminstrative time is needed to add the developers to the team.
  4. Almost no communication is required between team members.

I'll let you know the first time I see all of these at once.

Lost in Alabama
basically adding someone back to a project they had left (recent enough so they haven't forgotten anything too)
Mike Stone
"I'll let you know the first time I see all of these at once." Holding my breath!!!
Stu Thompson
+26  A: 

It only helps if you have a resource-driven project.

For instance, consider this:

You need to paint a large poster, say 4 by 6 meters. A poster that big, you can probably put two or three people in front of it, and have them paint in parallel. However, placing 20 people in front of it won't work. Additionally, you'll need skilled people, unless you want a crappy poster.

However, if your project is to stuff envelopes with ready-printed letters (like You MIGHT have won!) then the more people you add, the faster it goes. There is some overhead in doling out stacks of work, so you can't get benefits up to the point where you have one person pr. envelope, but you can get benefits from much more than just 2 or 3 people.

So if your project can easily be divided into small chunks, and if the team members can get up to speed quickly (like... instantaneously), then adding more people will make it go faster, up to a point.

Sadly, not many projects are like that in our world, which is why docgnome's tip about the Mythical Man-Month book is a really good advice.

Lasse V. Karlsen
I think software is inherently not such a project, so unless you are adding people to do non-programmer work (like creating images and translating text), you can safely say it WON'T help, with TMMM as reference
Mike Stone
+1, good example with the poster
+1  A: 

Yeah, you should read the book. Wikipedia also has an article on Brook's Law which discusses the two main caveats. Basically, the only time when adding people to a project doesn't make it later is when no time is needed to bring the people up to speed. Essentially: at the beginning, or at least before it's late, and when the people being added are extremely skilled in the particular domain of the project.

what makes you think I haven't read the book? thx anyway.
Ed Guiness
+1  A: 

Never. Just that fact that it takes time for you to train them, and for them to learn system. This should only be considered if the project is just starting to get behind and there is room for it in the budget. But it should never be considered when the project is approaching its deadline.

+5  A: 
  • If the new people focus on testing
  • If you can isolate independent features that don't create new dependencies
  • If you can orthogonalise some aspects of the project (especially non-coding tasks such as visual design/layout, database tuning/indexing, or server setup/network configuration) so that one person can work on that while the others carry on with application code
  • If the people know each other, and the technology, and the business requirements, and the design, well enough to be able to do things with a knowledge of when they'll step on each other's toes and how to avoid doing so (this, of course, is pretty hard to arrange if it isn't already the case)
Leigh Caldwell
+2  A: 

I come from the context-based school of testing (and life, for that matter). Hence, my answer would be, "It depends." It depends on the skills of the programmers, and how quickly they can be brought up to speed on what needs to be done. I also come from the pair-programming school (dependent on context, of course). I believe pairing will give you near-instant gains, provided people are willing to pair up, don't hate each other, know how to pilot as well as navigate, etc. You'll still be late, just less late. And since you're already late, shoot for quality.

To keep with your meme, You need this baby in a month, send another woman for moral support, and gestate faster, or something like that.

+4  A: 

Only when you have at that late stage some independent (almost 0% interaction with other parts of the project) tasks not tackled yet by anybody and you can bring on the team somebody that is a specialist in that domain. The addition of a team member has to minimize the disruption for the rest of the team.

+3  A: 

I suppose the adding people toward the end of the work could speed things up if:

  1. The work can be done in parallel.

  2. The amount saved by added resources is more than the amount of time lost by having the people experienced with the project explain things to those that are inexperienced.

EDIT: I forgot to mention, this kind of thing doesn't happen all too often. Usually it is fairly straight forward stuff, like admin screens that do simple CRUD to a table. These days these types of tools can be mostly autogenerated anyway.

Be careful of managers that bank on this kind of work to hand off though. It sounds great, but it in reality there usually isn't enough of it trim any significant time off of the project.

Giovanni Galbo
And how often is that actually the case?
Stu Thompson
virtually never ;-)
Mike Stone
+2  A: 

If software development is analogous to pregnancy, then could we say that a selection of modern v1 software products on a shelf are analogous to a hospital nursery, most of which are premature crack babies?

Stu Thompson
and I thought I was pushing the analogy...
Ed Guiness

Never. There are no such circumstances.

i like the confidence of your answer, even though its wrong. :-)
Ed Guiness
and all the other posts here, all wrong?
+3  A: 

An average programmer is rather unproductive about a month month after joining team, so that if the project is actually late (I'm speaking about 1 or 2 months to a first deadline) it's better to have some, unavoidable losses than increasing it by investing your programmers time into training a new team member.

The other thing you have to reconsider is a quality and organisation of work in your team. There were many cases where team had enough workforce to complete the task in time, but delayed it due to bad communication, waiting for the dependencies, slacking or as an effect of false savings which forced developers to spend more time later, on the other parts of application.

Also, I'm next man who recommends Fred Brooks book :]

In addition to 'unproductive about a month after joining the team', that a programmer is not fully ramped up and a solid contributor for two to six months. (and some never)
Stu Thompson

Depends entirely on the situation and code-base. If coded properly (i.e. following established design practices), it could make total sense. If you're looking at a bunch of code that follows no design practices, then you might be better off trudging through it.

what is this "coded properly" of which you speak?
Ed Guiness
+70  A: 

The exact circumstances are obviously very specific to your project ( e.g. development team, management style, process maturity, difficulty of the subject matter, etc.). In order to scope this a bit better so we can speak about it in anything but sweeping oversimplifications, I'm going to restate your question:

Under what circumstances, if any, can adding team members to a software development project that is running late result in a reduction in the actual ship date with a level of quality equal to that if the existing team were allow to work until completion?

There are a number of things that I think are necessary, but not sufficient, for this to occur (in no particular order):

  • The proposed individuals to be added to the project must have:
    • At least a reasonable understanding of the problem domain of the project
    • Be proficient in the language of the project and the specific technologies that they would use for the tasks they would be given
    • Their proficiency must /not/ be much less or much greater than the weakest or strongest existing member respectively. Weak members will drain your existing staff with tertiary problems while a new person who is too strong will disrupt the team with how everything they have done and are doing is wrong.
    • Have good communication skills
    • Be highly motivated (e.g. be able to work independently without prodding)
  • The existing team members must have:
    • Excellent communication skills
    • Excellent time management skills
  • The project lead/management must have:
    • Good prioritization and resource allocation abilities
    • A high level of respect from the existing team members
    • Excellent communication skills
  • The project must have:
    • A good, completed, and documented software design specification
    • Good documentation of things already implemented
    • A modular design to allow clear chunks of responsibility to be carved out
    • Sufficient automated processes for quality assurance for the required defect level These might include such things as: unit tests, regression tests, automated build deployments, etc.)
    • A bug/feature tracking system that is currently in-place and in-use by the team (e.g. trac, SourceForge, FogBugz, etc).

One of the first things that should be discussed is whether the ship date can be slipped, whether features can be cut, and if some combinations of the two will allow you to satisfy release with your existing staff. Many times its a couple features that are really hogging the resources of the team that won't deliver value equal to the investment. So give your project's priorities a serious review before anything else.

If the outcome of the above paragraph isn't sufficient, then visit the list above. If you caught the schedule slip early, the addition of the right team members at the right time may save the release. Unfortunately, the closer you get to your expected ship date, the more things can go wrong with adding people. At one point, you'll cross the "point of no return" where no amount of change (other than shipping the current development branch) can save your release.

I could go on and on but I think I hit the major points. Outside of the project and in terms of your career, the company's future success, etc. one of the things that you should definitely do is figure out why you were late, if anything could have been done alert you earlier, and what measures you need to take to prevent it in the future. A late project usually occurs because you were either:

  • Were late before you started (more stuff than time) and/or
  • slipped 1hr, 1day at time.

Hope that helps!

thanks for the thoughtful answer, i'll upvote when my vote supply is topped up
Ed Guiness
you put effort into this. good quality posting! bump it up!
Good list. However, I fear many projects are late precisely because they do not have everything you list...

Quite simply, none. If you're already late, adding people will only make you later due to ramp up time and an increase in communication channels.

Garry Shutler

With black box programming, it is easy enough to break out segments of a large project and pass them out to your programmers. The number of programmers that speed your progress is only limited by the number of simultaneously developed boxes your can design out of the system.

+1  A: 

adding new people on will kill your baby


In general, it is indeed a case of diminishing returns, however, if all other paths have been exhausted, other programmers may be able to be added at a cost factor of productivity, in small quantities.

For theoretical/conceptual illustration, a team of 3 might have 1 person added and get an additional 50% worth of that person's actual hours (if they started at the beginning of the project it would've been all 100%). The same team may also be able to add 2 more people at a factor of 30% each, but then adding 3 may mean a factor of 15%, which is worse than if there were only 2.

Troy DeMonbreun
As Fred Brooks points out, the fourth person has to communicate with the first three, *slowing them down*. The result of adding the fifth and sixth is even worse. In general, without good design, a SW team is an undirected, fully connected graph. Communications overhead goes up with (N*(N-1))/2.
Tim Williscroft
My numbers were just for theoretical/conceptual illustration. I haven't read TMMM, but I'd imagine that along with communication overhead there would also be other types of logistical overhead, though I would guess that TMMM probably covers that.
Troy DeMonbreun
+8  A: 

It shouldn't, but here is a rule:

If bringing on additional people speeds up a project, fire the first batch of people, and it'll speed it up even more.

+2  A: 

Obviously every project is different but most development jobs can be assured to have a certain amount of collaboration among developers. Where this is the case my experience has been that fresh resources can actually unintentionally slow down the people they are relying on to bring them up to speed and in some cases this can be your key people (incidentally it's usually 'key' people that would take the time to educate a newb). When they are up to speed, there are no guarantees that their work will fit into established 'rules' or 'work culture' with the rest of the team. So again, it can do more harm than good. So that aside, these are the circumstances where it might be beneficial:

1) The new resource has a tight task which requires a minimum of interaction with other developers and a skill set that's already been demonstrated. (ie. porting existing code to a new platform, externally refactoring a dead module that's currently locked down in the existing code base).

2) The project is managed in such a way that other more senior team members time can be shared to assist bringing the newb up to speed and mentoring them along the way to ensure their work is compatible with what's already been done.

3) The other team members are very patient.

+9  A: 

According to the Mythical Man-Month, the main reason adding people to a late project makes it later is the O(n^2) communication overhead.

I've experienced one primary exception to this: if there's only one person on a project, it's almost always doomed. Adding a second one speeds it up almost every time. That's because communication isn't overhead in that case - it's a helpful opportunity to clarify your thoughts and make fewer stupid mistakes.

Also, as you obviously knew when you posted your question, the advice from the Mythical Man-Month only applies to late projects. If your project isn't already late, it is quite possible that adding people won't make it later. Assuming you do it properly, of course.

+1  A: 

I think the {codesqueeze} post Adding People To A Late Project Makes It Later has some very good ideas about this problem

+2  A: 

I'm part of a project that has gone on more than twice as long as originally intended. Part of the problem is that neither of the contributors have enough time to work on the project around our other responsibilities. Adding a programmer or two who could spend a lot more time working on it would most certainly speed it up.

+1  A: 

If the current team is made up of monkeys at typewriters and the new programmer is a smart human.

You know, because he can just start from scratch.

Nathan Long
"Always use a scratch monkey"
Windows programmer
+2  A: 

I think adding people to a team may speed up a project more than adding them to the project itself.

I often run into the problem of having too many concurrent projects. Any one of those projects could be completed faster if I could focus on that project alone. By adding team members, I could transition off other projects.

Of course, this assumes that you've hired capable, self-motivated developers, who are able to inherit large projects and learn independently. :-)

Matthew Cole
+1  A: 

Simply put. It comes down to comparing the time left and productivity you will get from someone excluding the amount of time it takes the additional resources to come up to speed and be productive and subtracting the time invested in teaching them by existing resources. The key factors (in order of significance):

  1. How good the resource is at picking it up. The best developers can walk onto a new site and be productive fixing bugs almost instantly with little assistance. This skill is rare but can be learnt.
  2. The segregability of tasks. They need to be able to work on objects and functions without tripping over the existing developers and slowing them down.
  3. The complexity of the project and documentation available. If it's a vanilla best practice ASP.Net application and common well-documented business scenarios then a good developer can just get stuck in straight away. This factor more than any will determine how much time the existing resources will have to invest in teaching and therefore the initial negative impact of the new resources.
  4. The amount of time left. This is often mis-estimated too. Frequently the logic will be we only have x weeks left and it will take x+1 weeks to get someone up to speed. In reality the project IS going to slip and does in fact have 2x weeks of dev left to go and getting more resources on sooner rather than later will help.

If everyone in development and test

  • is co-located
  • communicates well
  • understands their role in the project

you may stand a chance at pulling in the schedule by some small percent.

Communication is the main barrier. Having everyone in one physical location is integral if you are throwing warm bodies on a project late IMHO.

It is risky no matter what, though, as The Mythical Man Month outlines in depth.

+4  A: 

Rather than adding programmers, one can think about adding administrative help. Anything that will remove distractions, improve focus, or improve motivation can be helpful. This includes both system and administration, as well as more prosaic things like getting lunches.

Good suggestion, and one that I think is in keeping with the spirit of suggestions in Mythical Man Month. ++
Ed Guiness
+1  A: 

Where a team is already used to pair programming, then adding another developer who is already skilled at pairing may not slow the project down, particularly if development is proceeding with a TDD style.

The new developer will slowly become more productive as they understand the code base more, and any misunderstandings will be caught very early either by their pair, or by the test suite that is run before every check-in (and there should ideally be a check in at least every ten minutes).

However, the effects of the extra communication overheads need to be taken into account. It is important not to dilute the existing knowledge of the project too much.

Bill Michell
So you're saying it might be helpful and it might not be helpful?
Ed Guiness
More or less. I'm saying that the accepted wisdom is that adding people to a late project will make it later, but under some limited circumstances, managed very carefully, you can get some useful extra work from an extra person.
Bill Michell
+1  A: 

If the extra resource complement your existing team it can be ideal. For example, if you are about to set up your production hardware and verify that the database is actually tuned as opposed to just returning good results (that your team knows as domain experts) borrowing time from a good dba who works on the the project next to yours can speed the team up without much training cost

This is actually a pretty good answer. More generally, if a project depends on knowledge of A B C and D, and programmers on the team know A and B, then adding programmers who understand C and D can speed up the completion. The people have to get along well and there are still size limits on the team
Windows programmer
+2  A: 

Reading the question makes me want to answer perversely:

When you add programmers to a team of zero people, then almost certainly the development would speed up.

And I guess the team could be zero if they have quit in disgust, fired for extreme incompetance, passed away (naturally or otherwise), or any other multitude of options.


Haven't seen that happening ever. Only under those circumstances when one is "lucky", I believe.

Salman Kasbati

Adding more people to a late project will only help if the sole problem with the project is not enough people to do the work. If there is one additional problem, adding people will most likely make that problem even worse.

J.T. Hurley