This is the second part of my article on The Science of Fear: Why We Fear the Things We Shouldn’t–and Put Ourselves in Greater Danger by Daniel Gardner.  If you have not read Part I of this article, please do so: The Science of Fear – Part I.  Part I describes the reasons behind our fears and Part II will discuss relevant risk numbers and how they relate to current events.

How Likely Is It?

Most of our exposure to dangers or risk in the media leaves out a crucially important factor.  What is the likelihood of it actually happening to you?  If you are told taking a new kind of birth control increases your risk of breast cancer by 20% compared to an existing type, that may sound bad but you have learned nothing useful.  If the existing risk is 0.10% and the risk of the new type is 0.12% (increasing from 1 in 1,000 to 1.2 in 1,000), that is essentially irrelevant if there is any advantage of taking the new type.  For example, fewer side effects or greater convenience.  In either case this risk is very low and the difference is probably less than the margin of error anyway.  You simply cannot make reasonable decisions about behavior without knowing actual baseline risks.

What is a Significant Risk?

In addition to knowing the actual risk you have to decide if that risk crosses any kind of threshold and what if any behavioral change you should take in response to it.  If you don’t take the time to understand the actual situation, you are doomed to be ruled by irrational fears.  Some risk is worth a response and some is not.  It depends upon the likelihood of the event happening and the cost of altering behavior in response.  You aren’t going to get that from media stories or what other people think.  Your caveman brain is simply not equipped to intuitively deal with risk in our modern and connected world.  Here is my personal view of various levels of risk.

• 25.0% (1 in 4) If I am at 25.0% risk of something dangerous, I consider that an enormous risk that requires action.  If I live to be very old, say 100, my lifetime risk of cancer is probably somewhere around 25.0%.
• 1.0% (1 in 100) Let’s say my annual risk of some danger is 1%.  To me that’s a pretty significant risk and if there are things I can do to reduce it, I will.  High mountain climbing might fall into this category.  I’ve read that around 3% of Everest climbers die on the attempt.  Even if I was capable of climbing Everest I wouldn’t because that risk is too high.  But there are people to whom that risk is worth it.  It is still relatively low and 97 out of 100 will come back alive.
• 0.1% (1 in 1,000) This is getting to the point where I personally don’t expend much thought about it.  Obviously if there is an easy way to avoid it without much cost or crimping my style, then I would.  Things like violence (not murder but assault) at school fall into this range.
• 0.01% (1 in 10,000) This is the level where some risk management experts (or legal institutions) starting talking about de minimis.  This means too insignificant for concern.  This level is de minimis for me.  This is in the range of the annual risk for dying in a car accident in the U.S.  I wouldn’t avoid driving anywhere at any time as a result of this risk and most people I know don’t either.  But, I fasten my restraints because they are no cost to me to do so and they also reduce the risk of injury which is far more likely than death.
• 0.001% (1 in 100,000) or 0.0001% (1 in 1,000,000) These are so microscopically unlikely I wouldn’t waste 1 second of my life worrying about them and I don’t think anyone else should either.  And yet you may be surprised at what falls into these categories or are even more unlikely.

Risks

32.0% – Rate of overweight children in U.S.
3.0% – Risk of death from climbing mount Everest
2.0% – Rate of women aged 50 having breast cancer
0.016% – Annual U.S. risk of childhood cancer
0.013% – Annual U.S. risk of death in a car accident
0.010% – Annual U.S. risk of death from the flu
0.0047% – Annual U.S. risk of being murdered
0.0028% – 2009 death risk from swine flu
0.0001% – Annual U.S. risk for accidently suffocating in your own bed
0.0001% – Annual U.S. risk for dying in terrorist attack
0.00007% – Annual U.S. risk of teenager or child being abducted by a stranger and killed or not returned
0.00006% – Annual U.S. risk of being murdered at school (e.g. Columbine)
0.0000013% – Annual worldwide risk of shark attack

Factoids To Make You Think

• There are probably 1,000,000 naturally occurring chemicals in foods and 50% of them are carcinogenic in lab tests
• If terrorists took down a commercial airliner in the U.S. every single week and you took a plane trip once a month, you would still be more likely to die driving to the airport than on the airplane.
• If you bought a lottery ticket on Monday, you would be 2,500 times as likely to die before the Saturday drawing than you would be to win the drawing.
• You are 30 times as likely to be killed by lightning than by a shark

What do you think?  Leave a comment and join the conversation.

Tagged as: fear, probability, Psychology, risk