Following up on Russ's observation at http://tree-tech.com/board/?topic=topic1&msg=808.

Russ suggested that ATA might be used consistently as an intermediate term and that ATA - TAr = TAincr (9th ed), with the provision that ATATAa only if TAa>30".

I've thought about this. I found that some of my own spreadsheets were set up this way. Mathematically it works. But on review I fould it confusing. ATA is more than a numeric term in a set of calculations. It is a concept and it indicates to the appraisal reviewer or user that an adjustment has been made. It is burdensome and confusing to have to check the math (assuming you know that it should be checked)to see if ATA=TAa or if in fact there has been a downward adjustment. In order to make such a check both terms would need to be presented anyway so it's not like you save space in the form or sheet.

I've changed my sheet to display both TAa and ATA. A TAa value is always displayed, this is field gathered data. An ATA value is displayed ONLY if an adjustment has been made. TAincr is calculated using TAa if ATA is blank and using ATA if ATA is not blank (a simple if-then statement).

As an aside I will also be setting up application of ATA adjustments to be an appraiser choice not an automatic function if TAa>30". Based on a recent case and discussions with other appraisers I find that the adjustment should be factually based, not methodologically mandated. There are cases where the benefits do not fall off as trunk size increases, but rather continue to increase with, or perhaps even beyond trunk size. (This departure from the Guide's standardized procedure would, of course, need to be noted.)

Reply to post by Scott Cullen, on June 20, 2000 at 07:28:13:

I had occasion to review an appraisal this morning. ATA was properly used with a downward adjustment since the DBHs were all >30". But the appraiser used a textual label "Appraised tree trunk area." It prompted me to double check the Guide to see if ATA might be referenced as "Appraised" as well as "Adjusted" trunk area leading to variable appraiser usages.

In fact there is no such confusion in the Guide. I also realized that the Guide terms are even more specific.

Both 8th (pp.16-24) and 9th (pp.37-45) Editions introduce the terms TA and ATA in connection with collecting and interpreting data about the appraised tree(s). Both 8th (p.59) and 9th editions (pp. 70-71) subsequently introduce the subscript modifiers a and r (TAa for appraised tree and TAr for replacement tree; 9th also introduces TAincr to describe the calculated difference) in connection with analysis and computation. This is all old ground covered in other threads and discussions.

Both 8th (pp.60-63) and 9th (p.71#12 & p.74 #'s 11&12 & p.75 #'s 11 & 12) subsequently and clearly introduce the term ATAa, distinguish it from TAa and clearly seem to intend that the appropriate term be used with the associated numerical value. There is no suggestion that ATA can be used as the label for either quantity at appraiser discretion.

SUMMARY. It seems clear that both 8th and 9th Editions intend TA and ATA to be data collection terms and TAa and ATAa to be used (along with TAr and TAincr) as analytical terms, representing and distinguishing very specific collected data and adjusted or calculated quantities. Using these specifc terms as intended will limit confusion in the preparation and use of appraisals.