Hello,

I am intrigued by two opposing concepts in business. A few years ago,
the CEO of P&G turned around the company with a very simple idea. They
began to concentrate on a core group of products as he believed that
these 'core group' of products based on his decades of experience in
sales would bring in the maximum revenues for the company.

We are now reading that increasingly 'specific market niches' outside
the core group are bringing in an ever-increasing amount of revenues,
see http://www.thelongtail.com/

1. Is this 'longtail' concept valid for individual brands/companies
such as P&G, UniLever and individual publishing entities by themselves
(i.e. making money from niche shampoos that P&G produces itself, or
for a publisher like McGraw Hill - making money from niche books that
are published by McGraw Hill themselves) or is it applicable only to
stores that stock not one but multiple brands from competitors also
... such as Walmart, Amazon etc.

I am also looking for the following:

2. Links to research on the former i.e. revenues/profit brought in by
a core group of products for a specific company. (e.g. McGraw Hill
makes most money from only x% of titles published per year)
3. Links to research on the latter i.e. longtail or similar concept. 

I know that the price I am offering is rather low, but I am asking
this question merely out of curiosity.

Thanks, in advance. 

TVR

The Long Tail concept applies to media and entertainment products. 
The economics of tangible consumer goods are different.  For example,
the cost to Procter and Gamble of bringing out a niche shampoo is
probably tens of thousands, if not millions, of times what it costs
iTunes to add a downloadable song to its catalog.  The Long Tail
concept says that iTunes wins by having tons of obscure material, but
that's because they can do that so cheaply.