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TRAQ to replace QTRA


sloth
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I think the important point that seems to me to have been overlooked within this emerging debate, is that all of these methodologies, systems, call them what you will, are simply tools in order to achieve a means to an end. Nothing more. (With PTI being training in order to use those tools in practice)

 

Somebody may choose to use Dewalt branded screwdrivers another may prefer Draper, or Stanley...... they all do the same job, just provide a different means in order to achieve that job.

 

Remember that in terms of tree risk assessment, it stems pretty much from the HSE sim...... which intimates that a practical and effective tree management process should echo the principles within the management of health and safety at work regs. i.e, carried out on a risk assessment basis.

 

In terms of the Courts, the only reason that a judge will even take any of these systems into account, is as demonstratable evidence that the "job" was carried out correctly - the "job" being that a tree has been appropriately managed based on it's level of risk.

 

As long as that box is ticked, and the defendant can show proactively that they have complied with the risk assessment process, it doesn't really matter if the tree was evaluated using THREATS, TRAQ, QTRA, or any other peer reviewed methodology.

 

So if CAS want to lean towards TRAQ as opposed to QTRA, to be frank, it's no real biggie. Certainly doesn't imply that one system is "better" or "worse" than the other.

 

I can't state definitively whether you are right or wrong on this. But I can say that I personally disagree very strongly that it's 'no real biggie'. Judges don't give a damn about acronyms, points, systems, but they are there specifically to adjudicate on duties of care and reasonable behaviour between members of society. They are there to imagine what the ordinary man should or shouldn't have done. and that includes whether a professional with a duty of care to a tree-owning client has covered his client's arse or his own. Preferably with something more convincing than a few microns of latex...

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I can't state definitively whether you are right or wrong on this. But I can say that I personally disagree very strongly that it's 'no real biggie'. Judges don't give a damn about acronyms, points, systems, but they are there specifically to adjudicate on duties of care and reasonable behaviour between members of society. They are there to imagine what the ordinary man should or shouldn't have done. and that includes whether a professional with a duty of care to a tree-owning client has covered his client's arse or his own. Preferably with something more convincing than a few microns of latex...

 

Hi Jules,

 

Apologies, I thought I was being clear that my comment regarding it being "no biggie" was in relation to CAS's choice of tree RA methodology, not the courts.

 

100% agree with regards to the Courts - which is why I posted that Judges only even look at these methodologies as evidential demonstration that a system had been used.

 

Hopefully that's clearer.

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Hi Jules,

 

Apologies, I thought I was being clear that my comment regarding it being "no biggie" was in relation to CAS's choice of tree RA methodology, not the courts.

 

100% agree with regards to the Courts - which is why I posted that Judges only even look at these methodologies as evidential demonstration that a system had been used.

 

Hopefully that's clearer.

 

Yes thanks. The CAS certainly isn't the arbiter of which system is better, but it's reason for preferring TRAQ to QTRA is some sort of endorsement of how imprecise the courts allow systems to be. Any truly unfit-for-purpose method of assessing and managing risk woud I expect be discovered by the courts. Judges are under quite a bit opf pressure (as one sees from written appeal decisions) to scrutinise methods and expertise.

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Yes thanks. The CAS certainly isn't the arbiter of which system is better, but it's reason for preferring TRAQ to QTRA is some sort of endorsement of how imprecise the courts allow systems to be. Any truly unfit-for-purpose method of assessing and managing risk woud I expect be discovered by the courts. Judges are under quite a bit opf pressure (as one sees from written appeal decisions) to scrutinise methods and expertise.

 

Not really sure it is either intended or should be taken as an endorsement of the courts opinion of one methodology over another.

 

CAS, politically (and I hate that word in this industry) has always had closer ties with the ISA and the ISA way - it just goes back to their roots and those peeps that formed that particular Association. Take their use of CTLA over Helliwell or CAVAT for example. Doesn't mean or even imply that one system is "better" or "worse" than the other, just that it's their own preference for which system most suitably fits their particular business model.

 

By the flip side, does the AA's preference of Helliwell over CTLA and/or CAVAT mean that the AA are saying Helliwell is "better" and CTLA/CAVAT is "worse"?

 

I don't really see that it does.

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I don't know the ins and outs of either but QTRA seems overly precise for something as subjective as tree hazard perception,

 

Hi Sloth

 

Just by way of clarification.

 

QTRA is not about ‘hazard perception’, it’s about risk assessment. A hazard is simply something that could cause harm. Risk and hazard are importantly rather different things. Something that is hazardous can have a very low risk. With trees, trying to manage hazards without consideration of the risk attached to them, will usually result in 'risk averse' decisions which waste resources and loose benefits.

 

I’m not sure what you mean by ‘perception’ here, but with regard to ‘precision’. QTRA makes an awful lot of effort not to be 'precise' because with tree risk assessment you can’t be. QTRA's inputs are in ranges, and its outputs are worked through Monte Carlo simulations for the very reason that you can't be that precise. I think there’s a pervasive confusion that numbers mean laser like precision and accuracy whereas words in such circumstances, even though they must have a measurable meaning and boundaries, are better because they are less precise.

 

There’s a neat illustration that highlights this issue. A Martian, who hasn’t been slowly and surely drawing up their plans against us, lands here today and is asked to forecast the chances of it raining tomorrow. If they said there’s a 50% chance of rain the next day, they are being very precise about the fact they have no idea. They could not express how clueless they are about the chances of it raining tomorrow with any more certainty.

 

Whilst on precision. I’m sure many of you following this thread will have seen I’ve uploaded a summary document of the TRAQ thread from last year. In it, one of the issues discussed is that a QTRA Probability of Failure (PoF) range 1 (in numbers 1/1 - <1/10) has three of four of TRAQ Likelihood of Failure ranges in it. Imminent and PROBABLE Likelihood of Failure ‘words’ are parked in the top end of PoF range 1, and the upper values of the POSSIBLE ’word’ are in there as well. Now that’s an incredible level of precision, but not obvious because the remarkable accuracy is disguised by the use of words; which can often have a significantly different meaning depending on whoever happens to say or hear them.

 

As for the CAS thing. My only observation is that it does seem odd to me they could potentially alienate their own members who are QTRA Users.

 

Cheers

 

Acer ventura

Edited by Paul Barton
Amendment requested by Acer Ventura
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CAS has closer links with the ISA and the ISA way. Take their use of CTLA over Helliwell or CAVAT for example. Doesn't mean or even imply that one system is "better" or "worse" than the other, just that it's their own preference for which system most suitably fits their particular business model.

By the flip side, does the AA's preference of Helliwell over CTLA and/or CAVAT mean that the AA are saying Helliwell is "better" and CTLA/CAVAT is "worse"?

 

We're a bit off TRAQ here (off track I mean!). A valuation system, just like a risk assessment system, requires backup. QTRA is supported by a significant training effort and a few people who have spent a considerable effort at updating manuals and documentation.

 

The Helliwell system has been highly dependent on one person, who has now retired. The AA's role in it reflects a certain momentum and inertia rather than deliberate effort, at least since 2006. CAS doesn't favour, as far as I know, CTLA over any other valuation system. My training course (now being run for the third time) looks at all valuation systems/methods as far as they are in the public domain with equal, but critical, oversight. It's the only course that covers CTLA but without the institutional support that, for example, QTRA gets it is inevitably weaker, whatever its strengths are.

 

The role(s) of our professional bodies is vital in the development, maintenance and continuity of these systems and it is just sad that we are so fragmented so that efforts are piecemeal.

 

Jon

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We're a bit off TRAQ here (off track I mean!). A valuation system, just like a risk assessment system, requires backup. QTRA is supported by a significant training effort and a few people who have spent a considerable effort at updating manuals and documentation.

 

The Helliwell system has been highly dependent on one person, who has now retired. The AA's role in it reflects a certain momentum and inertia rather than deliberate effort, at least since 2006. CAS doesn't favour, as far as I know, CTLA over any other valuation system. My training course (now being run for the third time) looks at all valuation systems/methods as far as they are in the public domain with equal, but critical, oversight. It's the only course that covers CTLA but without the institutional support that, for example, QTRA gets it is inevitably weaker, whatever its strengths are.

 

The role(s) of our professional bodies is vital in the development, maintenance and continuity of these systems and it is just sad that we are so fragmented so that efforts are piecemeal.

 

Jon

 

Well put. The difficulty I think lies in the absence of motivation to work on anything that doesn't have a commercial return. I felt this acutely after putting in about 8 hours reviewing and commenting on the draft Bats BS. Why bother? Well I suppose I have to answer that. I did it because the draft was unworkable as a Standard, and someone had to speak up or else no-one would use it. And bats would suffer. Nature needs all the help it can get against clumsy, greedy, ignorant people. But I'll get zero other tangible reward. I'll have to pay to buy the resultant BS.

 

QTRA and TRAQ are both commercially viable from what I can tell. Being a menber of CAS certainly is. I don't see the level of business being there to make Helliwell viable, CAVAT operates in a non-commercial environment. CTLA and the iTree suite have legs. Just.

 

I'd agree therefore with the correlation between use and back-up but also viability.

 

I plan to practice and a member of CAS without using either TRAQ or QTRA. Time will tell whether CAS hitching its wagon to TRAQ comes to reflect badly on it and therefore on its members.

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I wasn't fully aware of the background to the proposed changes from CAS so asked Mark Chester for an update - he has given this response:

 

A limitation of QTRA is that not only is there no minimum entry requirement, there is also no assessment of a candidate’s competency. Operators use the system under license. It therefore does not fit in to the CAS model. As such, the CAS Board of Directors has recommended that it should no longer be recognised as a CAS Competency.

The ISA’s Tree Risk Assessment Qualification (TRAQ), by contrast, has a minimum entry requirement and delegates need to be qualified to at least level 2 in arboriculture. Assessment follows two full days of classroom and field exercises, and consists of two practical tree inspections and a 100 question Multiple Choice paper, all of which is overseen by the ISA. It is critically acclaimed and internationally recognised. It also fits the CAS model.

 

Some more clarification. QTRA has had a mandatory test to be completed after training for nearly two years now. The candidates have to score 100% in the test or they do not become a Registered User.

 

As for qualifications and experience beforehand. You don’t necessarily need to know that much about arboriculture to use QTRA because it is a proportionate Target-led risk assessment, not an exercise in measuring and describing trees and all their defects. So why exclude other professions, or tree owners/managers, who know how their land is used, and can identify gross defects? In order to generate an unacceptable level of risk in the Tolerability of Risk Framework, the Probability of Failure range has to start from Benchmark Red 1. Such a tree would have gross and easily recognisable ‘defects’, or ‘habitat features’. Where arboricultural skill is needed is in interpreting the significance of defects where the Target value is high enough, or the tree has sufficient value, to warrant the detailed risk assessment. It’s up to the risk assessor to acknowledge and work within their limitations, and know when to seek further advice about the Target or Probability of Failure, whether they be an arborist or not.

 

Curiously, in my experience as a QTRA trainer, it is often the case that it is non-arborists who grasp the concept of tree risk assessment the easiest. With some arborists it can be the case that they have to first unburden themselves from an ingrained hazard abatement approach where they identify defects and then want to do something about them, irrespective of the risk level. They can be prone to assessing what could happen rather than what is most likely to happen. Just in case there's harm and someone afflicted with hindsight bias claims they could've foreseen it after the event.

 

Just as a matter of curiosity, does anyone happen to know what this 'CAS Model' is, and how QTRA fails to meet it?

 

I'd also be interested where the label 'critically acclaimed' comes from in relation to TRAQ? It implies that TRAQ's been critically reviewed and the outcome of the review was 'acclaim'. Anyone know where any of these reviews are?

 

Cheers

 

Acer ventura

Edited by Acer ventura
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Monte Carlo Simulation software apps are the way forward. Non-standardised canonical discriminant function coefficients all the way, long overdue. :thumbup:

 

Hear, hear! TimberCutterDartmoor.

 

Down with this sort of satanic science mangelwurzel thing. It be the Devil’s work I tell thee. This revelation was just visited upon me in the belly of an iron bird, returning to these god-fearing shores after an apprenticeship in a yonder land they call Salem. Whence, to inquisition a tree to tell if it be a baddun and not forsake it’s nature, I take a big bucket of sand, bury my head in it, pop a mandrake up my fundament, and wait for the disease of astonishment and the speaking of tongues. I’ve even cut off all me fingers and toes in case I become weak and get overwhelmed with an irresistible and demonic urge to try and measure.

 

Cheers

 

Acer ventura

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Just as a matter of curiosity, does anyone happen to know what this 'CAS Model' is, and how QTRA fails to meet it?

 

 

Acer,

 

An earlier post from Paul B contained an explanation by Mark Cheter of CAS -

 

"The Consulting Arborist Society recognises a number of skills whereby an arboricultural consultant can demonstrate competency. These are known as Areas of Professional Competency (APCs). The first APC, which was the starting point for founding the society back in 2003, was the Mortgage course. QTRA was added in 2005.

 

Several years ago, all of the courses were reviewed to ensure they fitted the model with assessment of competency. Lantra’s Professional Tree Inspector qualification was added at this time.

 

A limitation of QTRA is that not only is there no minimum entry requirement, there is also no assessment of a candidate’s competency. Operators use the system under license. It therefore does not fit in to the CAS model. As such, the CAS Board of Directors has recommended that it should no longer be recognised as a CAS Competency.

 

The ISA’s Tree Risk Assessment Qualification (TRAQ), by contrast, has a minimum entry requirement and delegates need to be qualified to at least level 2 in arboriculture. Assessment follows two full days of classroom and field exercises, and consists of two practical tree inspections and a 100 question Multiple Choice paper, all of which is overseen by the ISA. It is critically acclaimed and internationally recognised. It also fits the CAS model."

 

The salient point to take I think, is with CAS being the Consulting Arborist Society, but QTRA however being open/applicable/achievable to non arbs - thus, "QTRA does not an Arborist make", and thus CAS can not necessarily safely accredit a QTRA user as even being an Arborist, let alone a consulting level one.....

 

Which kinda defeats the overall purpose of the Consulting Arborist Society and what the organisation tries to achieve.

 

TRAQ however is tree specific, with training only open to peeps with Arb experience and quals, so thus more closely mirrors the aims of the society.

 

I certainly don't see it as an indication that CAS is implying one system is "better" or "worse" than the other, as the thread seems to have degenerated to. It is simply their choice, in relation to the aims of their organisation.

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