----- Original Message -----
From: John Flannigan
To: UK Tree Care
Sent: Friday, December 31, 2010 8:10 AM
Subject: Re: CAVAT
I mention this having had long experience of having my own research 'tested'
- it, like all research/new things tend to be all the better for it and if
CAVAT is robust then there's no problem. You raise an important point about
the literature and it troubles me that tools such as Helliwell
SC For instance it is not clear anyone knows whether the Helliwell basic
value unit is a benfits unit (an indication or measure of monetized income or
revenue) or a price unit (an indication or measure of what someone is or was
willing to pay for trees or woodlands). A great deal is made of the unit
being adjusted for inflation periodically and thus being realistic, but
nothing is made of what the unit represents. The original published papers
by Rodney Helliwell may suggest the unit may have reflected what LAs were
willing to pay (WTP) for conservation woodland in the 1960s but I'm not clear
on that (could well be my fault) and if it is a price unit just how it was
derived from the LA acquisitions. Nor is it clear that peer review elicited
that. The Helliwell System is cited a number of times in Sinden & Worrell,
1979 Unpriced Values - Decisions Without Market Prices. Economist Sinden was
an undergraduate mate of Helliwell's at Bangor. But this book does not test
or inquire at the roots of the Helliwell System, it simple sees it as useful.
And indeed the Helliwell System has had over 40 years of usefulness. But
IMO at least it might hjave been more robust if its underpinning were well
understood.
and CAVAT are
especially weak in this area. On the other hand VTA and CODIT are
particularly strong.
John
On 31 December 2010 11:37, Scott Cullen <dscottcul@xxxx.net> wrote:
>
> ----- Original Message -----
> From: John Flannigan
> To: UK Tree Care
> Sent: Friday, December 31, 2010 6:10 AM
> Subject: Re: CAVAT
>
>
> Thanks Dave
>
> I'm not doubting the hard work and determination needed to bring CAVAT to
> a
> wider audience. My concern is that it has become standard Arb practice
> without any obvious crictical analysis of it by independent observors,
> particularly those that know about valuation. Bearing in mind it is a
> valuation tool I think this is essential. Without such input I am
> reluctant
> to use it, or accept reports where it is used.
>
> So, for me the jury is out awaiting some independent corroboration.
>
> John
>
> SC John, I think this illustrates the strength and weaknesses of "peer
> review." Dave is correct that "peer review" takes various forms and the
> "peer reviewed" journal is just one of them. The journal venue is the
best
> known and perhaps most respected. Certainly it is more independent than
the
> developer group itself or its clients (the LTOA CAVAT committee and the
LTOA
> users). But economists and RICS type valuers have training and experience
> biases that may blind them to the role of CAVAT, some of the CTLA methods,
> Norma Granda and so forth). I'm told that Shigo had a very difficult time
> getting published on CODIT, initially, because his training was in
pathology
> and his concept flew in the face of traditional tree physiology. If you
> look at any of Shigo's journal papers they (in sharp contrast to the very
> conversational style of his arb books) they are incredibly densely ground
in
> literature citations. I think that's what has been lacking for CAVAT and
> largely for CTLA as well.
> SC Jumping down to Dave's comments below, should we be anticipating an FC
> "formal study"of CAVAT?
>
> Scott
>
>
> On 29 December 2010 10:26, David Lofthouse
<David.Lofthouse@xxxxxxx.gov.uk
> >wrote:
>
> > I've spoken with the originator and here are some of the comments we
> agree
> > on.
> >
> > On peer review, there was an 18 month series of sessions with an LTOA
> > sub-group which resulted in the population density adjustment among
> other
> > things.
> > It was looked at for Trees in Towns 2.
> > TDAG commented.
> > Post release, the FC of course, have looked into it extensively most
> > recently, although they still haven't published their formal study.
> >
> > As with most of the LTOA hosted/produced documents, its live and is
> updated
> > regularly. Anyone, member or not is free to contact, comment or suggest
> > changes (front page of website).
> >
> > And of course everyone out there commenting on the string on UKTC is
> peer
> > reviewing it now! Which is quite a lot more reviewing than many tools
> get.
> >
> > On training: Its quite likely that further sessions will be run through
> the
> > LTOA though this might take a little while to arrange in the new year.
> >
> > Happy New Year
> >
> > Dave
> >
> > Dave Lofthouse
> > Arboricultural Manager
> > Greenspaces
> > Environment and Regeneration Dept,
> > London Borough of Merton,
> > Tel 0208 545 3659
> > Fax 0208 545 3237
> > Mobile 0790 1510 496
> >
> >
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