Ed,
Well, I surely regret that I've given such an undesirable impression. What I was attempting to show were the results that follow from making certain defensible assumptions, at least defensible on the surface. I'm not saying any particular result is absolutely the right one, just showing patterns, asking questions, and stating preferences based on my experience with the equipment. I've tested the Nikon 440 enough to know the patterns it gives. But I don't always factor them in because I don't have input coming from an independent source, such as a tape drop. On any given measurement, I can't be sure of whether to leave a distance alone or reduce it by 0.5 yards. However, examining the patterns can point to a choice. I suppose the number I would have like to have settled on is 158.2 feet - the high. But, I am obviously not doing that. The actual height of Thoreau most likely falls between 156.0 and 157.0 feet - if the laser returns are from the top most twig. The safest course to avoid a number that is too high is to adjust the top distance readings by reducing each by 0.5 yards. I can make a good case for leaving the bottom distances alone. If I follow this strategy for the set of measurements taken and average the results, I get 156.7 feet. From how my Prostaff 440 laser behaves on bright versus not bright targets, and bright versus non-bright backgrounds, this is a defensible course, whatever the result. It happens to be 156.7. I wish it were 158.2, but can't accept that value. So, why go through the process at all? Because, Andrew's tape drop added an additional piece of information that steered me away from the high end measurements. Bob ----- Original Message ----- From: "Edward Frank" <[email protected]> To: [email protected] Sent: Sunday, December 6, 2009 2:15:37 PM GMT -05:00 US/Canada Eastern Subject: Re: [ENTS] Settling the issue on Thoreau Bob, You can't pick and choose among the various measurements you get for a tree to generate a number you want to achieve. There needs to be a consistent criteria for accepting or rejecting certain numbers if you feel they are invalid and if they meet the rejection criteria. Juggling the laser numbers to match the results of a tape drop doesn't count. I realize you are not trying to manipulate the measurement data, but that is what you are effectively doing in this situation. The data is what it is, and should not be arbitrarily prettied up to make it better. That is certainly the impression anyone reading these posts will get. Ed Check out my new Blog: http://nature-web-network.blogspot.com/ (and click on some of the ads) -- Eastern Native Tree Society http://www.nativetreesociety.org Send email to [email protected] Visit this group at http://groups.google.com/group/entstrees?hl=en To unsubscribe send email to [email protected] -- Eastern Native Tree Society http://www.nativetreesociety.org Send email to [email protected] Visit this group at http://groups.google.com/group/entstrees?hl=en To unsubscribe send email to [email protected]
