Measuring lethality in reduced expected heartbeats

post by chaosmage · 2014-01-03T14:14:40.145Z · score: 5 (10 votes) · LW · GW · Legacy · 27 comments

Some of us here are already familiar with Micromorts - a unit that stands for a 1 in a million chance of dying. The wikipedia page lists a number of sample values. One obvious example is that smoking 1.4 cigarettes is one micromort. This is a good tool for comparing the relative dangerousness of activites - for example, if you fly in a jet in the US, your micromorts per mile from increased background radiation are twice the micromorts per mile from terrorism. And you can compare activities to baseline average risks of death, given as about 39 per day (averaged over all age groups and sexes).

However, people suck at imagining small probabilities. So a different unit, which we used in a group exercise at the Secular Solstice in Leipzig, is the number of expected future heartbeats. While Micromorts are a step away from empirical reality, expected heartbeats are another step in the same direction. But the concept got good feedback, it makes people think about life in a new way, so I thought I'd just share it here.

The average human heart gets to beat about 2.5 billion times - about 100000 times per day. So a micromort is around 2500 expected heartbeats. So you can translate, say, smoking a cigarette into a cost of about 1800 expected heartbeats (or about 80 seconds of life expectancy). And maybe that'll help people optimize their behavior in ways that Micromorts, due to their microprobability nature, aren't very good at doing especially for those who aren't very habitual Bayesians.

27 comments

Comments sorted by top scores.

comment by James_Miller · 2014-01-03T19:17:15.988Z · score: 16 (16 votes) · LW · GW

Why not just use time and measure things in terms of the reduction in the expected number of seconds, minutes, or days of life because of the dangerous activity?

comment by Kawoomba · 2014-01-03T14:36:12.685Z · score: 13 (13 votes) · LW · GW

So you can translate, say, smoking a cigarette into a cost of about 1800 expected heartbeats (or about 80 seconds of life expectancy).

You got tachycardia or somethin'?

comment by faul_sname · 2014-01-03T20:56:42.636Z · score: 5 (5 votes) · LW · GW

No, chaosmage is just a very active hummingbird. Hitting keys on the keyboard takes work when you only weigh 10 grams.

(1800 heartbeats in 80 seconds is 1500 beats per minute, as opposed to the human average of around 80 beats per minute)

comment by AlexMennen · 2014-01-03T19:12:15.685Z · score: 3 (3 votes) · LW · GW

This comment made me notice a flaw in measuring lifespan in heartbeats: inducing tachycardia would increase the number of heartbeats you experience (unless it decreases your actual lifespan by more than that).

comment by Wes_W · 2014-01-03T19:21:28.614Z · score: 0 (0 votes) · LW · GW

Resting heart rate is negatively correlated with cardiovascular fitness: the lower, the better. So far as I know, the point of measuring lifespan in heartbeats is that tachycardia does in fact kill you that much faster. I am not a medical professional, and it's probably not wise to take "conservation of lifetime heartbeats" too literally, but that's the general idea.

comment by gjm · 2014-01-03T20:05:33.643Z · score: 2 (2 votes) · LW · GW

I'm fairly sure it isn't proportional: someone with a heart rate of 40bpm isn't going to live twice as long as someone with a heart rate of 80bpm. (But might well live 3x longer than someone with a heart rate of 120bpm, which I guess would indicate a serious medical problem.)

I'm not an expert, though, and will gladly be corrected on this.

comment by Metus · 2014-01-03T14:50:55.478Z · score: 12 (14 votes) · LW · GW

I can't visualise 1800 heartbeats, it seems so abstract and I know that my heartrate varies wildly depending on my emotional state and physical activity.

80 seconds however is something I can see every day. Why not go with that?

Then again, excellent initiative to visualise something like death probabilities. Our brains aren't naturally rational, we have to help. I am convinced that with the right translations, like this, we can reuse existing neural structures.

comment by solipsist · 2014-01-03T18:40:30.197Z · score: 4 (4 votes) · LW · GW

Associating cigarettes with time might help me in reverse. Cigarettes disgust me. My self-image strongly states that I am a person who doesn't do stupid things like smoke cigarettes. Would I smoke a pack of cigarettes per day? Hell no! Would I smoke three packs per day? That would be suicide.

But I do waste time. 80 seconds per cigarette works out to 30 minutes per pack. If I thought of wasting 30 minutes the same way I think of smoking a pack of cigarettes, I would waste a lot less time.

comment by Wes_W · 2014-01-03T19:13:14.483Z · score: 1 (1 votes) · LW · GW

If smoking a pack only cost you 30 minutes, then you'd have to smoke a pack a day for 48 years to shorten your lifespan by just 1 year, which IIRC is a lower risk than smoking actually poses.

100,000 beats per day is ~70bpm, so 1800 beats is 25 minutes. I've just noticed that I don't actually know how many cigarettes are in a pack - a dozen or so? - so that's around 5 hours. 48 years of smoking would cost you a decade of expected life, which (again, IIRC) is in the right ballpark.

This does mean the conversion rate of wasted time: cigarette disgust is lower than the 80-seconds figure implies. I hope this does not too much undermine the idea's usefulness to you.

comment by NancyLebovitz · 2014-01-03T19:31:36.437Z · score: 3 (3 votes) · LW · GW

20 cigarettes in a pack, typically. A few brands have 25.

comment by [deleted] · 2014-01-03T20:44:16.396Z · score: 1 (1 votes) · LW · GW

If smoking a pack only cost you 30 minutes, then you'd have to smoke a pack a day for 48 years to shorten your lifespan by just 1 year, which IIRC is a lower risk than smoking actually poses.

The figure I was familiar with, and the one most frequent in the first page of Google results for each cigarette shortens your life by, is 11 minutes.

comment by NancyLebovitz · 2014-01-03T22:36:00.848Z · score: 0 (0 votes) · LW · GW

That seems high.

Smoking shortens life by about ten years-- but not so much if you stop by age 40. This may imply that if we get decent anti-aging tech, smoking won't be a serious risk. How hard would the tech be to not be bothered by cigarette smoke?

Let's assume someone who didn't stop smoked for 40 years-- two packs a day. That's 40 x 365 x 40 = 584,000 cigarettes. Divide that into 10 years worth of minutes, and it comes out as .9 minutes, assuming I set up the calculations properly.

comment by Yosarian2 · 2014-01-04T14:46:38.256Z · score: 1 (1 votes) · LW · GW

This may imply that if we get decent anti-aging tech, smoking won't be a serious risk.

Not necessarily; more likely, it just means that damage is cumulative over time. Most people don't start smoking when they're 45, so it's not really a direct comparison.

Also, smoking seems to negatively affect brain health as well, which is problematic since reversing brain degradation might be harder then other types of anti-aging technology.

comment by Caspian · 2014-01-05T01:07:32.003Z · score: 0 (0 votes) · LW · GW

I think there's an error in your calculations.

If someone smoked for 40 years and that reduced their life by 10 years, that 4:1 ratio translates to every 24 hours of being a smoker reducing lifespan by 6 hours (360 minutes). Assuming 40 cigarettes a day, that's 360/40 or 9 minutes per cigarette, pretty close to the 11 given earlier.

comment by [deleted] · 2014-01-03T20:48:29.966Z · score: 1 (3 votes) · LW · GW

I can't visualise 1800 heartbeats,

On reading this in the Recent Comments sidebar, I thought “1 heartbeat = 1 second, 1800 seconds = half an hour” in less time than it takes me to tell left from right.

comment by NancyLebovitz · 2014-01-04T15:25:52.863Z · score: 0 (0 votes) · LW · GW

How long does it take you to tell left from right?

comment by [deleted] · 2014-01-04T16:07:07.683Z · score: 0 (0 votes) · LW · GW

Usually around one second.

comment by Metus · 2014-01-04T08:44:24.228Z · score: -2 (2 votes) · LW · GW

You must be so smart. My stupid brain can handle ready-made 30min faster and more reliably than the conversion.

comment by [deleted] · 2014-01-04T09:34:10.007Z · score: 0 (2 votes) · LW · GW

Mine too. What's your point?

comment by V_V · 2014-01-03T19:11:43.941Z · score: 10 (10 votes) · LW · GW

Heart rate varies. Moreover, humans are as bad as visualizing large number as they are at visualizing small numbers. How can you visualize 2.5 billion heart beats?
It seems to me that sticking to expected years, months or days makes more sense.

comment by DanielLC · 2014-01-04T04:44:22.863Z · score: 4 (6 votes) · LW · GW

Micromort measures the probability of dying. Reduced expected heartbeats measures the reduced lifespan. You cannot convert between them.

For example, it might be that smoking one cigarette and driving one mile both are one micromort, but smoking doesn't kill you for a long time while driving kills you immediately. Thus, driving reduces expected heartbeats by more.

I'd consider reduced expected lifespan much more useful. Although I don't see why you're measuring it in heartbeats instead of seconds or minutes or something.

comment by Metus · 2014-01-04T08:46:55.588Z · score: 0 (0 votes) · LW · GW

This is another thing that just came to my mind: You have to distuingish between how the survivor's distribution of lifetime looks like, as stated in your example with driving. Some die very young, but most live. With smoking however you can reasonably say that they reduce their lifespan proportionally, in addition to some risk to die very young. I know of no good way to visualise this.

comment by John_Maxwell (John_Maxwell_IV) · 2014-01-08T09:27:54.775Z · score: 1 (1 votes) · LW · GW

So you can translate, say, smoking a cigarette into a cost of about 1800 expected heartbeats (or about 80 seconds of life expectancy).

It sounds to me like your heart is beating very fast.

comment by hyporational · 2014-01-03T23:22:01.752Z · score: 1 (1 votes) · LW · GW

One obvious example is that smoking 1.4 cigarettes is one micromort.

Doesn't this assume the risk accumulates linearly and irreversibly? I'm pretty sure you can't do that.

comment by ChristianKl · 2014-01-06T01:58:14.251Z · score: 0 (0 votes) · LW · GW

It does assume linearity but not irreversibly.

You can calculate conditional probabilities based on chances of quitting and not quitting cigarettes in the future.

Linearity is a more interesting issue. There the model of cancer being caused by a single mutation. In that model a single cigarette has a certain chance of creating a single mutation. If you deeply believe in that model you can justify linearity to some extend.

In reality cancer however seems more complicated. But it's hard to calculate the micromorts of a single cigarette. We don't have a good theory for doing so.

It similar to other regulation of substances that harm us. We can measure in a lab how much of a substance you need to give rats to kill 50% of them. It's plausible that a 1/1000 of that substance can still do harm to the rats but we have no clear way of finding out.

We just have models that try to use the existing data to produce risk estimates that are as good as possible. Then we use those estimates to make policy. The models are best we have at the moment so they seem to be better than nothing.

comment by hyporational · 2014-01-06T08:21:56.698Z · score: 0 (0 votes) · LW · GW

You can calculate conditional probabilities based on chances of quitting and not quitting cigarettes in the future.

This would make micromorts very situation dependent which would diminish their value as a statistical tool. Ex smokers would get far more micromorts from a single cigarette than people who're just trying smoking.

In the case of smoking, a certain number of pack years become a permanent but still a diminishable risk factor past certain age. Before that age, both COPD and cancer risk can revert back to normal levels if you quit smoking. This makes perfect sense in a model where the body is able to repair itself but the repair mechanisms can be overwhelmed with a sufficient stimulus.

Using a linear model pretty much ignores the body's ability to heal itself and the ability to remove harmful substances.

We can measure in a lab how much of a substance you need to give rats to kill 50% of them. It's plausible that a 1/1000 of that substance can still do harm to the rats but we have no clear way of finding out.

Many substances are useful with the right dosage, and lethal with an overdose.

comment by ChristianKl · 2014-01-06T22:59:05.690Z · score: 0 (0 votes) · LW · GW

This would make micromorts very situation dependent which would diminish their value as a statistical tool.

Even an acitivity like driving a car is situation dependent. Careful drivers have a different risk than reckless ones. At the same time the table doesn't show you separate values.

This makes perfect sense in a model where the body is able to repair itself but the repair mechanisms can be overwhelmed with a sufficient stimulus.

I agree with that model, but I would point out that there are plenty of people out there who consider the bodies ability to heal itself from cancer pretty nonexistent.