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Subject: Color measurement spreadsheet

Color measurement spreadsheet

From: Roy Perkinson <royperkinson>
Date: Friday, February 11, 2000
Last October, at the conference in Chicago called "The Broad
Spectrum," I described a Microsoft Excel spreadsheet that I wanted
to share with anyone who would find it useful. Mounting this on the
web turned out to be a bit more complicated than we had expected,
but we're now ready to send it on its way.

As I discussed in my presentation (which is expected to be published
in the future), the purpose of this spreadsheet is to automate and
simplify assessment of colorimetric data. By following the
guidelines I've suggested--always making five measurements whenever
measuring a particular color -- the spreadsheet will handle the
calculations required to subject the data to two tests: 1) a test
for equal variance, and 2) the Student's T test, which is
well-suited for small sample populations (less than about 30

For example, if one wants to compare an "old" set of data (taken at
some time in the past) with a "new" set of data obtained recently,
this spreadsheet will help determine whether the color one has
measured really has changed. In practice, after one has entered both
the old and new data, a message will appear stating whether or not
the difference between the old and new values of L* is statistically
significant. Similar messages will appear for a* and b*. The results
are calculated using what statisticians call a 95% confidence level.
In ordinary language, this confidence level or degree of probability
is often called "statistically significant."

If you would like a copy of this Excel file, direct your web browser
to one of the following two web sites. Note: the first URL is for
those who use PCs. The second URL is for Mac users. Please note that
for reasons neither I nor our webmaster understand, we've noticed
that after logging onto the PC site and as you are trying to save
the file to your own computer, you may notice a cryptic dialogue box
that says something about "Read only..." It appears that no matter
which of the buttons you select, the file can still be saved to the
desktop (or wherever on your computer you'd like to put it) and that
it still opens normally once you have saved it. If all else fails,
let me know and I'll email you a copy by attachment.

For PC users:
For Mac users:

(note that the extension "xls" on the Mac version is required for
some reason known only to our webmaster)

Roy Perkinson

                  Conservation DistList Instance 13:44
               Distributed: Wednesday, February 16, 2000
                       Message Id: cdl-13-44-002
Received on Friday, 11 February, 2000

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