**Subject:** Color measurement spreadsheet

From: Roy Perkinson <*royperkinson*>

Date: Friday, February 11, 2000

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 measurements). 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: <URL:http://www.mfa.org/conservation/downloads/pccolor.xls> For Mac users: <URL:http://www.mfa.org/conservation/downloads/maccolor.xls> (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