Risk

NeilHolden

Absolutely true. Would you start/continue a dive if your OC regulator started to free flow? Sure you have another, but that is your backup. Would you turn off the cylinder valve and then ignore the fact that your redundancy has gone? Yes you can turn it on and off [the first stage] in case of an emergency - but continuing the dive is not an emergency! (except to get out)

Risk is an individual thing, but this should be tempered by common sence and training. (unfortunately common sence is not (IMHO) that common!) There is nothing 'macho' or 'exciting' about starting or continuing a dive with nothing to bail out to, or with faulty kit.

You can always dive tomorrow, or next week/month/year.

You can't dive if you are dead!

If the kit isn't right abort/bail the dive and enjoy the scenery. If you don't 'feel' right, or for whatever reason you might come up with the default setting should be 'don't dive'. Everything needs to be 'right' to get the green light. Otherwise talk about the problem in the pub afterwards, submit a near miss report so we can all learn from it, and ignore those who say 'go on it will be all right'.

I have two plastic from teeth from following that advice when playing rugby and forgetting my gum shield! Luckily not in a position to kill me!

There is only one persons opinion that really counts - your own.

Risk is a personal thing - some are prepared to take more than others, but we should all be prepared to say 'NO THANKS' if the risk seems too much and we should not pressure each other to 'continue regardless'. Ignore peer pressure - I learned the hard way, my teeth still hurt occasionally!

Remember, we can always dive tomorrow, or next week/month/year but only if we survive the risk.

The decision rests with us all.

Neil

__________________
Diversi Veshi Tem

Underwaterbear

Good discussion, and one very relevant to many of us here whether we realise it or not. Risk has been my profession for the last 7 years or so. I am a professional ecologist specializing in the management of threatened and endangered species. I write probability based models to assist agencies with the decisions they are obliged to make. This is a long prelude to a two simple points I wanted to raise:

1. Humans have time and again been documented as appallingly bad at assessing percieved risk.

2. Realise that the probability of a catastrophic event is insignificant compared with the consequence of that event when there is only a single trial. It's your life you're playing with.

Cheers
AB

Genesis

Just a quickie....

Uh, that's not accurate.

If you want to look at probability as irrelavent than you cannot responsibly dive - at all. After all, the consequences......

Probability is always a factor in risk evaluation. It has to be.

The problem is that we've got a piss-poor handle on the probability side of the equation, and what we can do to change it to our advantage - the consequence side we all know about.....

__________________
"A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American."
http://www.denninger.net
http://www.diversunion.org/liability.htm - Fix the Diving Cert racket

Underwaterbear

Okay, quick retort...

Yeah I agree, as far as a classical interpretation goes if for example you're in the insurance business or the builder of CCRs where there are many trials. But the means by which the probability of an event is calculated make no sense when an outcome is binary (as it is when there is only one trial). Whilst it is strictly correct that expectation theory (risk x consequence or any other formulation) can be used as an index or measure of risk I believe it leads to poor decisions because it understates the weight of the consequence. This is part of why we percieve risk so poorly (my point 1).

My contention is that knowing the rate of occurence doesn't matter in a trial of one. Something either happens or it does not. If the consequence is undesirable, being responsible is about eliminating the event as far as possible or placing contigencies in place to mitigate the consequence. If there is no way to eliminate or mitigate then this is where the decision is made to proceed or not and this is where the personal "risk thermometer" comes into the process. The example from earlier in the thread about Grand Prix drivers "liking it hot" is a classic example they participate in a very dangerous sport but are (especially these days) highly risk averse. Improving the odds to your advantage (as you put it) is something only your insurance company should care about.

Genesis

Sure it does.

We are all going to die of SOMETHING. For example, you might be hit by lightning. Do you never go outdoors, thereby reducing your risk? Probably not. Why? Because the risk of the bad thing happening (Zzzzaaaap!) is small in the first place, so reducing it further by staying inside has low marginal utility.

One must also consider the marginal utility of the contemplated activity. That utility value varies from person-to-person and event-to-event.

Many people judge the risk of a bad outcome from smoking to be acceptable to them - even though the actual risk is nearly 50% over a period of a few decades! Those aren't real good odds! But if you call each cigarette a "trial", then it doesn't look as bad.

Look at the person who chooses to engage in IV drug use. The risk (of death by HIV, if you don't OD first) is quite high - perhaps 50%? Yet the perceived benefit is high enough that people do it.

Or, for that matter, commercial fishing. The risk of death is quite high, yet the reward (a paycheck) is quite material too. Some people consider the balance acceptable, others not.

When it comes to recreational activities nobody other than the participant can accurately calibrate the utility value, since there is no objective measurement possible.
The two are completely decoupled in any honest assessment, and the utility value must also be considered; there is actually a triplet of data to weigh.

Since the penalty for a bad trial is typically death in this endeavor, you can call the consequence "infinite". However, this does not necessarily mean that the risk is unacceptable, because that consequence will visit all of us some day and the personal utility value from diving may be extremely high.

Therefore, the real question is what percentage of trials will lead to the bad consequence? For virtually everyone, if the risk approaches that of winning the lotto, people will find it acceptable.

Some will find the odds of a bad trial at 1:1000 acceptable, because they find the utility value extremely high. Others will calibrate the number of acceptable risk to utility at 1:100,000, and still others will want the 1:17,000,000 or so of the lotto....
By definition a risk scenario in which the consequence is death has an absolute "bad consequence".

This position would lead to a call for an absolute ban on diving.... and yet, we're not debating that... I don't think......

__________________
"A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American."
http://www.denninger.net
http://www.diversunion.org/liability.htm - Fix the Diving Cert racket

Underwaterbear

Impressive. I've read plenty of this stuff too. I don't want to go on arguing sematics with you (although I'm sure we'd both enjoy it ) I'll simply close out by suggesting that continuing to think from a clasical interpretation of probability as it applies to risk assesment and the calculation of utilities, or expectation or whatever you like to call the same thing, is flawed when it comes to making real world decisions.

I'm going to opt out of the discussion here as I think to get my point across and to debate your (well made) points will take more keystrokes than I can spare today. Lets continue it over a beverage if we ever meet!

Regards,
AB

NeilHolden

I agree this is a good discussion, but some of the words are a bit long!

The whole point in risk reduction is so that we can continue doing the activity tomorrow, and next week etc..etc.. So that the 'marginal utility' of said action can continue.

Unfortunately some seem to get hung up on the 'MUST DIVE NOW' train of thought, and take uncesessary risks (IMHO) to achieve what is in effect only one dive. Or badly assess the risk of kit failure/weather worsening/own ability etc. A lot of this ability to assess risk comes with experience (ie having got it wrong before and survived) - but that may come too late.

I mitigate as many risks as possible, so that I may continue diving in the future. If the activity is so good that we are prepared to take risk then surely that is the aim?

One of my (flying) instructors told me this when I started training:

"Everyone starts out with two bags, one full of luck the other empty of experience. We hope that our bag of experience is full enough before our bag of luck runs out!"

A very apt saying - directly applicable to any number of the activities that I have undertaken - including diving of all sorts!

The idea of risk mitigation is to give us time to fill the bag of experience!

Neil

__________________
Diversi Veshi Tem

dantheman

I use the following trite phrase in my oc tech classes:

"Experience is what you get immediately after the time you need it most."

--dan