Tree Risk Assessment Review

2023-04-24 4:42 PM | Admin (Administrator)

VALID's Risk Assessment Model

We're at the end of another successful tree risk training and advisory tour of NZ & AU. On this trip, we've been told some Aussie Arborists are not yet sure about upgrading their approach to tree risk with VALID because of a point raised in Peter Gray's Tree Risk Assessment Review for Arboriculture Australia's 'The Bark' magazine (2020).

Tree Risk Assessment Review

Advantages & Disadvantages
In the article, Peter suggests a disadvantage of VALID is:

"The underlying mathematics running the App have not been made available for peer review. VALID claims to have used the services of a respected and independent maths professor to develop and test the App but this must be accepted without any chance to review and criticise it."

This 'disadvantage', is in fact an 'advantage'.

Here's why.

Our Risk Professor
First, the 'Maths Professor' is in fact a 'Risk Professor'.

He's Professor Willy Aspinall. Willy is the Cabot Professor in Natural Hazards & Risk Science at Bristol University, and he said this about the 'underlying maths'.

"We have stress-tested VALID and didn't find any gross, critical sensitivities.
In short, the mathematical basis of your approach is sufficiently robust and dependable for any practical purpose."

VALID is the only tree risk system that's been put together with a Risk Professor, who's an internationally distinguished expert in assessing risk in the natural environment. Surely, this is an 'advantage', and not a 'disadvantage'.

3 points about making the 'underlying maths' available.

1) It would give away our intellectual property, and anyone could copy it. Similarly, Google doesn't make its search algorithm available.

2) We're planning to write a paper with the Professor once he's less busy being an expert witness on the risk to Japanese nuclear reactors from an Aso volcano super-eruption .

Or on the fallout from the New Zealand Whakaari/White Island volcanic eruption.

3) How the matrices are constructed in TRAQ is not available for peer review. Neither are the Monte Carlo simulations in QTRA available for peer review.

Another consideration is, the underlying maths won't help a Duty Holder or Risk Assessor with their decision-making. Indeed, some might think they know better and try to numberwang the model to game the risk they want.

We were also told, some Duty Holders and Arborists are concerned about how they would explain their decision making if they ended up in court.

If you use VALID, it's extremely unlikely you'll end up in court. If you did, as long as you don't make a green decision when it should be red - which is incredibly difficult to do - we've got your back.

The Bolitho Test


© VALID is a not-for-profit organisation