If you've heard of Daniel Kahneman, you'll likely have read his excellent Thinking Fast & Slow, where he shares his Nobel Prize winning work into behavioural economics. All that fascinating stuff about how ingrained biases often have reasonably foreseeable impacts on our decision making.
His most recent interest has been a collaboration with Oliver Sibony and Cass Sunstein, exploring the role of 'Noise' in decision making.
Noise is the significant variability in decisions you get where there shouldn't be any. Such as when Doctors diagnose disease, or when Judges sentence criminals.
Or when Arborists make tree risk assessment decisions.
Earlier this year, More or Less' Tim Harford had a short chat with Daniel Kahneman about how to reduce Noise by practising Decision Hygiene.
https://validtreerisk.help/Noise
If you want to dive into the Decision Hygiene part, it starts at 5.50.
What was eye-opening about this discussion into the benefits of practising Decision Hygiene is that it's embedded in VALID.
Arborists' tree risk assessments are notoriously noisy. Ask 10 Arborists to risk assess a tree and you'll likely get 12 very different decisions.
One of VALID's benefits is we've designed it to reduce this Noise. When it comes to Occupancy and Consequences, consistent and good decision making is so 'quiet' you don't need to be an Arborist to do it well.
In tree risk assessments, we get most Noise with Likelihood of Failure decisions.
When you make your Likelihood of Failure decision in VALID, you're guided to evaluate all the likelihood of failure attributes, independently of each other, before you make a decision.
This VALID approach to Likelihood of Failure decision making is what Daniel Kahneman is calling Decision Hygiene.
Whilst rummaging through some of the UK's dusty Risk & Regulation Advisory Council archives, we strayed across 'A Worrier's Guide to Risk'. David Spiegelhalter (Chair of the Winton Centre for Risk and Evidence Communication at the University of Cambridge) put it together for them in the noughties.
It's a great guide to thinking about risk, some of which applies to trees, on one side of paper - our favourite length for a subject.
We're now into a prolonged hot dry spell of weather. When this happens, anxious Duty Holders often get in touch about managing the risk from Summer Branch Drop (SBD), or Summer Limb Drop (SLD), or Sudden Branch Drop (SBD), or Sudden Limb Drop (SLD).
What to do? The uncertainty about what to call SBD, or SLD, is often matched by similar uncertainty about how you should manage the risk.
Should you put up signs?
Fence trees off?
Prune them?
Fact-checking the risk The overall risk from SBD is mind-bogglingly low.
From the data, the risk is so low, our risk of death from driving for the few minutes it takes to cover about 5km/3mi is higher than from SBD over a whole year. Finding a microscopic straw-coloured needle in a gargantuan haystack
Despite this mind-bogglingly low risk, fear-mongering from Risk Entrepreneurs*, claiming legal action is likely if the risk were to happen and it wasn't managed or assessed, has had some anxious duty holders putting up confusing and ineffective signs.
Is standing, lollygagging, or laying down fine?
What we know We know the overall level of risk from SBD is so low it's Acceptable.
We also know, Arborists can't tell the difference between branches that have a high likelihood of failure from SBD, and those that have a low likelihood of failure.
That means, warning signs make no measurable reduction to a risk that's already Acceptable. In fact, the costs of commissioning and managing these signs are grossly disproportionate to any claimed reduction in the risk. Linger near trees at your peril
Photo Credit - Paul Barton
Exposing yourself in public Worse still, the ineffectiveness of these signs may backfire and create an opportunity for a Risk Entrepreneur to act as an expert witness in the extremely unlikely event of someone being killed or injured by SBD. It'd be all too easy for them to claim you hadn't managed the risk well enough, and you could've done more.
Why didn't you put up more signs?
Why didn't you fence the tree off?
Why didn't you prune the tree?
Or, if the visitor wasn't an English speaker, why didn't you translate the sign into other common languages?
If you're a Duty Holder, or advise one, worry not. We've got your back on this one with our Summer Branch Drop Guide. An antidote to risk entrepreneurs
In short, you don't need to do anything to manage the risk unless you have a repeat offender.
We've also got a whole range of guidance of our Risk Management page.
*Risk Entrepreneur "Treecare professionals who thrive on maximising the perception of risk in order to create standards for which they are perfectly placed to provide profitable solutions."
Rick Haythornthwaite, Risk & Regulation Advisory Council
This is the one-side-of-paper Summary of our Tree Risk-Benefit Management Strategies.
The history We were first asked to put this together by the Department of State Growth, Tasmanian Government, when they were adopting VALID. It's role was to explain what the Strategy is all about to the departments strategic decision makers. The Summary proved such a useful communication tool, it found its way into the Government Agency template, and we've released it for general use.
How to use the Strategy Summary It works at two levels. If you're a Duty Holder, you can grasp the complete Strategy within the time it takes to take a few sips of tea or coffee. Similarly, if you're an Arborist you can quickly catch the eye of a busy potential client and add value to your service.
Active Assessment - Every 5 years? We think a 5 yearly Active Assessment frequency in Zones of High Confluence is reasonable, proportionate, and reasonably practicable. It's what many Duty Holders are adopting. Here, there's strength in numbers singing from the same hymn sheet if a risk is realised and a claim or enforcement action is being threatened. However, this is a Duty Holders decision. If they have a lower 'risk appetite' and are prepared to spend more money, we don't have a problem with a shorter frequency of Active Assessment. Just edit the PDF or Word Template.
PDF Strategy Summary v8.0.pdf
WORD TEMPLATE Strategy Summary v8.0.dotx
Here are the main fonts used in the Tree Risk-Benefit Management Strategies.
Museo 700 Source Sans Pro
Georgia is the body text and that should already be on your computer.
We have several free Tree Risk-Benefit Management Strategy templates that we've released under a creative commons licence.
You can read all about them on our Risk Management page, and download them as pdf files.
We're happy to share them with you as Word Template .dotx files as well, which makes it easier to customise the few sections that you need to. We've included the fonts that you might not have.
The is the version for a Homeowner. It's the simplest with a Policy and management by Passive Assessment; which is keeping an eye out for Obvious Tree Risk Features you can't help but notice.
PDF Homeowner TRBM Strategy v8.0.pdf
WORD TEMPLATE Homeowner TRBM Strategy v8.0.dotx
The is the version for a School, College, or University. It's similar to the Landowner one, where the Duty Holder has no trained Arborists as staff.
PDF School TRBM Strategy v8.0.pdf
WORD TEMPLATE School TRBM Strategy v8.0.dotx
The is the Landowner version. The main differences between this and the Government Agency one is there aren't voting stakeholders that you're looking to help understand. So there's no Introduction. There's also no trained Arborist on staff, but this can easily be changed in the Plan.
PDF Landowner TRBM Strategy v8.0.pdf
WORD TEMPLATE Landowner TRBM Strategy v8.0.dotx
Here are the fonts used in the Tree Risk-Benefit Management Strategies that you might not have installed.
The is the Government Agency version, which is the most comprehensive. It's written with Introduction section to explain what the document is about to 'stakeholders'. Also, Arborists are part of the staff, which isn't the case with the other Strategies.
Of course, if the Duty Holder doesn't have Arborists, then it's to edit the document to explain that they'll be hired when necessary. The Landowner Strategy covers this.
PDF Government TRBM Strategy v8.0.pdf
WORD TEMPLATE Government TRBM Strategy v8.0.dotx
Museo 700Source Sans Pro
We've updated the Obvious Tree Risk Features Guide to include a new panel for Construction Damage; which will also be in the Tree Alert App.
The idea of including Construction Damage is for two reasons.
1) It's an extension of encouraging high volume, low effort, citizen science tree risk assessment (Passive Assessment) to include substantial damage to the stem or roots of a tree.
2) We thought it might also be useful to take advantage of having this many eyes on the ground, day in day out, who can report where a development is going horribly wrong.
An additional panel, and smaller images, means we've been able to increase the number photos in the guide.
The formatting of the Guide has been updated to include heading, subheading, and paragraph numbers, so it flows with our free Tree Risk-Benefit Management Strategies.
Obvious Tree Risk Features Guide
Here's the new VALID Likelihood of Failure voting card for v2 of the Tree Risk App, which is in development.
If it's new to you, VALID (from where we get our name) gives you 5 chapter headings and 15 subheadings, that can affect a tree's Likelihood of Failure.
When you're carrying out a tree risk assessment, and have got to the tough Likelihood of Failure decision, VALID gives you a structure that guides through the factors you should consider.
At its simplest level, VALID is a checklist of things to think about and you're welcome to this voting card we use in training.
The most important change is:
DEFECT to DECAY We'll finally be rid of any mention of the red DEFECT word in VALID's publications. Those of you who have been there from the beginning will know this has been a quest for some time.
The first subheading under DEFECT is section modulus. That's because if you don't have a grasp of section modulus, and are relying on t/R ratios, you can't make a reasonable decision about the significance of strength loss from decay.
If you're not a Validator, who's been trained to use the Tree Risk App, here's their guide on how they go about using the current version to get to a base rate colour. You should get a sense about how this elegant and sophisticated approach helps you with your likelihood of failure decision making from this.
Likelihood of Failure | Decision Making
Day 2 of Validator tree risk training is all about making robust Likelihood of Failure decisions. If you follow this guide, it's really difficult to get it wrong. If anyone tries to game the risk to get it where they want it to be, it's really obvious where they've got it wrong, and that's what they've done.
You can keep up with all latest news about tree risk by staying in touch.
We'll send you an occasional short dispatch from the front line every few months or so.
You'll also be first to know when new events are coming up.
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