So Mark, which of your three different averages should one use as the average amount a longitudinally corrected is "off" (either positive or negative) on any randomly selected day of the year. Is the correct answer your mean absolute error of 7.2 minutes? Is this what I should tell my sundial customers?
Thanks for answering, John Carmichael >John Carmichael asked: > >> Is the average EOT correction over the course of the entire year equal to >> about seven or eight minutes? from (16+15)/2/2=7.75 min.. As 16 minutes is >> about the extreme correction on Nov. 1st. and 15 minutes is the other >> extreme corroction in mid Febuary. Does anybody know the exact average? > > >I reported on several different error statistics for EoT in a paper I gave >at the Seattle 1998 NASS shindig. And I've promised Fred Sawyer that a >write-up of my talk will eventually be submitted to _The Compendium_. >Oh, for a few more hours in the day.... > > >Mean error: 0.0 minutes >(The average error over one year, taking into account the sign of EoT.) > >Mean absolute error: 7.2 minutes >(The average error when taking all EoT errors to be nonnegative.) > >Root-mean-square error: 8.7 minutes >(The square root of the average of the squares of all EoT errors.) > > >~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ > Mark Gingrich [EMAIL PROTECTED] San Leandro, California > >
