I have it, but currently only in PL/1 (mainframe) and perl. I also have
documentation from 1980 on the method but I would have to dig for it. Let
me know if you can't get Excel code and want what I have.
However, I discovered to my distress that the Bureau has changed the
rules on us for 2000. In 1980 and 1990 medians were computed from the
grouped data as reported in STF3. This means that 17 intervals were used
in 1980, 25 in 1990. When I couldn't get medians that matched the Bureau's
for the General Demographic Profiles, I guessed it was because there are
fewer intervals than there will be in the full SF3. I contacted the Bureau
and found out that the medians are calculated "behind the scenes" from 39
intervals, although only 17 intervals will be in SF3 (according to prelim
doc, and the numbers 17 and 39 are from memory--they are close if not
So this means we will not be able to exactly replicated Census
methodology. It also means we can't calculate standard errors for medians.
I calculated the median income for Cook County from the GDP using Pareto
and it is about $500 different than the Bureau's number. It should be
closer when we get the real SF3.
I posted the Bureau's response about this on the State Data Center
Listserve. If anyone wants it I can send them a copy or post here.
On Tue, 18 Jun 2002, Daryl Scott wrote:
I am trying to calculate the median income for a
region using the Pareto Interpolation method like the Census Bureau. I cannot find the
correct equation. If I did find it, I did not know how to convert it into an Excel
formula. Does anyone have an Excel spreadsheet that has the necessary formulas for
calculating medians using the Pareto Interpolation method? Thanks, Daryl
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