I am on a project which has multiple staff (each with their own role).  
Developers: 2.5
Business Analyst (BA): 0.5
Quality Assurance (QA): 0.5
Project Management (PM): 0.25

I am looking for a study that shows the inefficiency in having
different staff in each of the roles of BA, QA, and PM.  For one they
need to come up to speed as they enter the project at different times
through out the year.  They also need to communicate with each other. 
Lastly, their is a context switching cost as staff needs to
concentrate on more then one project at a time.  All of this adds
administrative costs and does not relate to generating real project
deliverables.

I am looking to quantify these ineffiecencies (all three) and come up
with an argument for combining these roles into one.  Any extra
arguments you can derive are appreciated.

Since you got neither comment, nor request for clarifcation,
apparently your premise is not provable and/or you have us confused.
In these days of half truths and false inferences, It seems important
to have several more or less independent confirmations to get customer
confidence and get the tasks done properly on the first try most of
the time. Which is to say 3 heads are better than one. 5 heads may be
excessive: I presume you have employees who do the grunt work and you
encourage, the employees to make suggestion reguarding the project
proceedure. Likely you have a chief execitive who at least spot checks
the details of the various projects, especially if there is a hint of
a problem. Perhaps you have a salesman = customer rep, who may take an
active interest after the sale.
I'm guessing you have fewer than 20 employees, including execitives
and grunts, so part time gives you back up in case both the persons
who understand the project throughly leave permanently or for a
significant amount of time.   Neil

Please do not attempt to answer my question.

mahrens917--

Neilzero-ga is not a Google Answers Researcher (his username would be
in purple rather than black if he was.)  So even if he answers your
question, you would not have to pay for it.