I need to find out how long, on average, a property sits on the
current market before it is sold. This is intended to be an average
for all properties, whether listed by a broker or a "for sale by
owner", whether it is commercial or residential.  I need this
information from a qualified source OTHER than the National
Association of Realtors which says that a property sits on the market
for 4 weeks before going to contract (www.realtor.org), this is their
average for Realtor Members only.

NAR compiles this information, someone has to do it or else there are
no known figures. If you want figures for the entire industry, and
they are not compiled, hmmm...

Frankly, I work for my brother in the RE industry, 4 weeks sounds
correct to me, but since my brother is a member of NAR, this opinion
is useless to you.