A few years ago, I was paid by a company to write a research report
about a real estate market. I used statistics provided by the company
and wrote the piece, which was then published by the company as a
research report. The company created charts for the report and
published it under company logo. My question is:

Since I wrote the work and never signed away my rights to it, can I
legally display it as a writing clip on my Web site? I asked the
company for permission to post, and the company refused.

Other relevant data: 

- The report is from 1999, and all actual data about the real estate
market from that time is now in the public record.
- My name is not on the research report, which is common practice for
documents like this.
- I can, if necessary, produce an invoice for the project and a check
stub from the company's payment as proof that I did the work.

Please cite a reputable legal source when providing an answer.

Hi vercingatorix,

Firstly, please read the "Important Disclaimer" at the bottom of the
page. We have no legal authority, however, due to some previous
copyright research that we've made, we can help you to make an
informed decision on whether to pursue this any further. I've listed
several websites which explain the "Work-for-Hire" rule and it will be
up to you to see how your personal circumstances fit into it. If you
think you have a case, please consult an attorney.

The most important item that you have in your possession is your
contract with the party who paid you to do the work. Read it
carefully. What you are looking for is the "Work-for-Hire Agreement",
in other words, whoever hired you to produce some work, owns the work
you produce *if both parties signed an agreement to that effect*.

Working with Freelancers:
What Every Publisher Should Know About the "Work For Hire" doctrine: 
"Without an agreement signed by both parties before work begins, the
status of the parties' relationship (and copyright) may be in
dispute."
http://copylaw.com/new_articles/wfh.html

What is a "Work for Hire"?
"The default copyright scenario is that a creator owns his or her
work. For another party to own the work, it must be set forth in a
writing."
http://law.freeadvice.com/intellectual_property/copyright_law/work_for_hire.htm

Who owns what? (UTexas):
"The author is usually the owner.
* Except when the work-for-hire rules apply: The author's employer owns work(s)
   o created by an employee within the scope of employment, or
   o that fall within one or more of the nine statutory categories,
where the agreement commissioning the work is documented in writing
and signed by the author before work begins"
http://www.utsystem.edu/OGC/IntellectualProperty/whowns.htm

Work-for-Hire Agreements:
http://www.adcmw.org/about/work_for_hire.html

Cornell Legal Information Institute (find in page: "hire"):
http://www4.law.cornell.edu/uscode/17/101.html

THREE EXAMPLES OF AN AGREEMENT:

1) Sample Work-For-Hire Agreement:
http://www.uwsa.edu/fadmin/gapp/gp27at_b.htm

2) Work-for-Hire Agreement:
http://www.creativebusiness.com/CBworkforhire.pdf

3) Work-for-Hire Agreement:
http://www.oba.uiuc.edu/prch/cpm/cpm3h.pdf

FIND A LAWYER:

FindLaw: Search "Intellectual Property" as well as "Copyright":
http://lawyers.findlaw.com/

I hope this helps. If you have any questions, please post a
clarification request before rating my answer.

Thank you,
hummer

No search terms were used as we have the relevant websites bookmarked.
However, if you search for "work for hire", you'll get lots of
interesting returns.

Permit me to add just a bit to hummer's excellent answer.  You own the
copyright to the report and can legally post it under copyright law
UNLESS (1) you were an actual employee of the company (as opposed to
an independent contractor) and you created the report during the
course and scope of your employment, in which case they own the work
as a work made for hire; or (2) you were an independent contractor AND
you signed a contract with them assigning (giving) to them the
copyright in the report you authored; or (3) the work was "a work
specially ordered or commissioned for use as a contribution to a
collective work, as a part of a motion picture or other audiovisual
work, as a translation, as a supplementary work, as a compilation, as
an instructional text, as a test, as answer material for a test, or as
an atlas" AND you agreed with them in writing that it was a work made
for hire.  See 17 U.S.C. Section 101 at
http://caselaw.lp.findlaw.com/scripts/ts_search.pl?title=17&sec=101.