The most recent report on breastfeeding statistics from Ross is
_Breastfeeding Trends Through 2000_, available as a pdf file (16
pages):  http://www.ross.com/aboutRoss/Survey.pdf  (This is the
survey that the Chicago Parent magazine article drew its numbers
from.  I wonder if Ross will publish the 2001 report soon?)

"Questionnaires are mailed to a probability sample of new mothers
selected from a list of names that represents approximately 82% of
all national births.  In 2000, 1.4 million questionnaires were
mailed, 117,000 each month, with a response rate of 31%.  Results
from the survey were weighted using demographic characteristics that
have been traditionally associated with breastfeeding."

So their sample is something more than an opportunity sample, and
something less than an ideal statistical representation of all
mothers.  It does go beyond simply sending surveys to moms who sign
up for baby clubs.  However, they do not say where or how they get
the list that represents 82% of births.  I believe I've heard in the
past, though I can't find this mentioned anywhere now, that Ross uses
a variety of sources such as public birth records and newspaper
announcements to make their list.

Whatever the source of their survey list, they do indicate that they
employ statistical techniques to attempt to make the responses
representative of all mothers.

Margaret
Longmont, CO

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