- This is missing the most important thing which is why HRs are so damn useful. It's because (a) survival analysis is very statistically powerful, but (b) many survival curves do not follow a very well-described parametric function. The genius of David Cox was in realizing that, when proportional hazards hold, you can just cancel out the unknown survival function and get the multiplicative hazard ratio immediately, in a statistically powerful and statistically efficient manner. Extremely useful if you are, say, trialing a novel chemotherapy drug and want to end your trial ASAP to get everyone on the intervention arm if the drug actually works.
The places where proportional hazards gets squirrely (very long observation times, crossing curves) are a small fraction of the use cases of survival analysis, and dunking on them for "not being Bayesian" or whatever misses this broader context.
- > Extremely useful if you are, say, trialing a novel chemotherapy drug and want to end your trial ASAP to get everyone on the intervention arm if the drug actually works.
They are extremely useful for that, yes.
- From the article:
> This is essentially the observation Keyfitz made in his 1977 paper, “What Difference Would It Make if Cancer Were Eradicated?” Cancer is responsible for 18 percent of deaths, so does that mean eradicating it would increase lifespan by 18 percent, or around 13.6 years? Nope, Keyfitz says, it’s only 2.3 years.
A very interesting thought!
- The most important part of this for a living human being is touched on at the end. You only die once. Life expectancy is an ensemble mean over a population, and "you are not a population". You need to try to avoid risks that are going to kill you personally, not risks that affect aggregate life expectancy (there's overlap of course). Tinkering with HR-translated-to-life-years I think actually blurs that focus for individuals.
The worst case is a risk that has a low ensemble HR and low life years impact, but will kill you personally very soon if you take the wrong action. Eating peanuts has an HR of 1, unless you are prone to fatal anaphylaxis from peanuts. HRs are useful for (and biased towards) doctors protecting as many humans as possible, but as an individual you should try to discover your peanut allergies as early as possible and protect yourself against them.
- Relatedly, a common confusion is the use of probability in ergodic and non ergodic processes. The best example I have come across is that of a million people playing Russian Roulette with a six chamber revolver, in repeat mode.
At any instant, only about 1/6th will get shot. However, your own probability will rapidly converge to 1 of being shot.
- Yes, exactly. Absorption barrier.
- This is an important point that many people miss.
Describing a benefit (or cost) over a population doesn’t directly translate to decision making at the individual level.
We can say that you should alway take a bet that has an 80% probability of a 10x payout, because the outcome is positive, it wouldn’t be smart to bet your entire network as many outcomes are negative.
- > 54,786 chambers
365 days * 75 years = 54,750 chambers. 365.25 days (for leap years) gets to 54,788.
Where did the two days go?
- 365.24 when rounded to two decimal places
- I read it, and it seems like the core formula is ΔL ≈ ln(1 / HR) × 12.93 years (for U.S. males). It also gives you an easy way to approximate and interpret HR values from health studies, like an HR of 0.90 roughly translates to a little over a year of added life expectancy. Makes it easier to read those papers.
Personally, I found it interesting. But what I'm curious about is this: are there any studies where the lower your exposure to risk, the shorter your lifespan gets?
I've been thinking about this because I recently saw a story about an ultra wealthy guy who tried a reverse aging experiment and ended up with an incurable disease. This person probably had the best diet in the world and received top tier care, so how did he end up with something like that? It makes me wonder, maybe the human body just rejects reverse aging itself. Maybe we're wired to die because that's how species diversify. Just curious.
- > This person probably had the best diet in the world and received top tier care, so how did he end up with something like that?
If you lower your chances of dying of every common thing, your relative chance of dying of a rare or incurable disease goes up. If I cured every disease but cancer, my odds of eventually dying of cancer would be very high.
- I think there’s just a decent component of “random chance” involved. You can live a healthy life and still die too young, or you can be a lifelong smoker who lives to 90.
When thinking about the impact of behaviour on health, it talks about humans in aggregate, not on an individual level.
- >so how did he end up with something like that
Is it not possible that the interventions were the cause of the disease? There's a lot about the body we don't understand, if you're mainlining supplements daily and doing blood transfusions on the regular you're messing around with a delicate biochemical balance.
- You're thinking of Bryan Johnson. He has autoimmune gastritis, it's not exactly a death sentence.
- Statistics and other lies.
One interesting point the article touches - there was a study concluding that if you quit smoking at 40 your life expectancy basically equalizes with people who did not smoke in their life. It is an encouraging message that it is never too late to quit. Then again it also sends a different message - you can smoke as you wish in your 20s.
Just yesterday I saw an article on Instagram that they are putting smoked meats and sausages and similar products in the came cancerogenic category as smoking. Which again one one hand states that meats are very bad for you. On the other hand it makes smoking not so bad as you would think? Because people are eating sausages and meats cooked on open fire for thousands of years?
Some guy on Diary of CEO states that rice are basically a poison because they are pure sugar. If you want to live healthy you should definitely drop the rice out of your die. Then again a billion of people eat rice every day. What gives?
We want to have all this information because we want informed decisions in our lives. If we are analytical we even want formulas and graphs just like in this article. What we don't want is to give things to chance and genetics.
Different breeds of dogs have life expectancy difference of ~50%. People of course are not so different in their size but we need to always keep this in mind. You can live as healthy as you like but you always have a ticking bomb in your DNA. What I still am not getting is how much living healthy impacts the outcome versus the genetics. It might be a hopeless fight to e.g. stop eating the brisket if your lungs have an expiry date of 55 years.
- > Just yesterday I saw an article on Instagram that they are putting smoked meats and sausages and similar products in the came cancerogenic category as smoking.
My understanding is that this is a statement of how confident we are in the evidence that smoked meats and sausages are carcinogenic. Essentially, we are very sure that smoking is very carcinogenic and we are also very sure that smoked meats and sausages are a tiny bit carcinogenic.
- > Just yesterday I saw an article on Instagram that they are putting smoked meats and sausages and similar products in the came cancerogenic category as smoking.
But not the same lung capacity impact category .. the emphysema rates from smoked meats are considerably lower than those from smoking.
- I think it was just cancer overall. One kills you lings, another kills you gut, heart and etc.
We know that smoke itself is really really bad for you. Open fire is bad for you.
Sitting around campfire with a glass in your hand and a guitar might be really really bad for you.
- I feel like you're ignoring the size of each of these impacts.
Sitting around a campfire once a month will likely increase your cancer risk. But it increases your cancer risk way, way less than smoking a pack of cigarettes every day.
Similarly, the World Health Organization is confident that smoked meats increase cancer risk. But that makes no statement about how much more likely you are to get cancer. I'm confident that eating undercooked chicken raises my risk for salmonella; I'm equally confident that eating a raw and expired piece of chicken also raises my risk of salmonella. But I would not say that each of those raises my salmonella risk by the same amount.
See the difference?
- The biggest danger of smoking is not cancer, it's cardiovascular diseases. You are comparing a mosquito to an elephant.
- Just cancer might be the equivalence.
Smoking itself cause damage and disease that isn't limited to just cancer though.
- To me it sends the message that people who quit smoking tend to live longer than people who don't, but not that the act of quitting smoking had anything to do with anything. Specifically, if someone without the mindset to naturally quit smoking sees that study and quits only to hopefully live longer, they may not benefit nearly as much as someone who actually cares enough to more generally quit harming themselves.
