I am looking for data that describes the business outcome when a
traditional bricks and mortar retailer adds e-commerce to it's
marketing mix.  Do in-store sales drop, do they stay the same, do they
increase?  MUST HAVE ANSWER TODAY

This is such a general question that it defies any sort of answer
because there are so many factors involved, for example:

What type of business?

Is it one of those businesses that could benefit from ecommerce?

Is the business now being adversely effected by ecommerce?

What is the profile of its customers?

How good is the website? (You might like it but would the prospective
punters?)

How competitive is the business?

My best guess is that the website will have absolutely no effect on
the bricks and mortar business, at least initially.

it is a big box type business and currently has an extensive website
showing what it offered - but does not "sell" through the
internet.....i am look for experiences of other retailers that would
support the decision to begin "selling".....i.e., when internet
selling was added, did the volume go up in the "box" or stay the same,
or decrease...................

I don't have any data for you, but my opinion is that it would range
from negligible to no effect on your comparable store sales.  These
are non competiting markets.

Certainly a California customer will not shop at your New York store,
but they can buy from your website.