[cVwEq]

"Secondary drowning" is another term people use to describe another drowning complication. It happens if water gets into the lungs. There, it can irritate the lungs’ lining and fluid can build up, causing a condition called pulmonary edema. You’d likely notice your child having trouble breathing right away, and it might get worse over the next 24 hours.

Both events are very rare. They make up only 1%-2% of all drownings, says pediatrician James Orlowski, MD, of Florida Hospital Tampa. [1]

[1] https://www.webmd.com/children/features/secondary-drowning-d...

[young_unixer]

1%-2% doesn't seem "very rare" to me.

[dmos62]

What kind of intuition do you have about 1%-2%? I've a crappy grasp of probability. I'd say 1-2% is like being quite certain that you'll experience this or that within 50-100 tries/repetitions. That sounds rare to me. In case of life or death it's not a risk I'd tolerate, but I'd call it rare.

[young_unixer]

My intuition comes from other uses of "rare" and "very rare" in medical fields.

"In Europe a disease or disorder is defined as rare when it affects less than 1 in 2000 citizens." [1]

""" In the United States, the Rare Diseases Act of 2002 defines rare disease strictly according to prevalence, specifically "any disease or condition that affects fewer than 200,000 people in the United States", or about 1 in 1,500 people. This definition is essentially the same as that of the Orphan Drug Act of 1983, a federal law that was written to encourage research into rare diseases and possible cures.

In Japan, the legal definition of a rare disease is one that affects fewer than 50,000 patients in Japan, or about 1 in 2,500 people.

However, the European Commission on Public Health defines rare diseases as "life-threatening or chronically debilitating diseases which are of such low prevalence that special combined efforts are needed to address them". The term low prevalence is later defined as generally meaning fewer than 1 in 2,000 people. Diseases that are statistically rare, but not also life-threatening, chronically debilitating, or inadequately treated, are excluded from their definition. """

[1] https://www.eurordis.org/content/what-rare-disease

[2] https://en.wikipedia.org/wiki/Rare_disease

[wutbrodo]

That's 1 in 2000 of the entire population. 1/100,000th of the US population drowns every year, which means that 1% of drownings has an annual incidence of 1/1million.

(This is annual vs lifetime but if you do the rough math under some basic assumptions, you end up easily within what you're defining as "rare")

[saagarjha]

Even with a 99% probability, there’s about one chance in three that you wouldn’t experience it if you tried a hundred times.

[dmos62]

How does that work?

[notafraudster]

Let's say you roll a dice with 100 sides. If you roll a 1, you die. If you roll anything else, you live. We want to know the probability you will die if you roll the dice 100 times.

One way we could do this is look at the probability you'll roll it on the first roll... then the probability you won't roll it on the first roll but you will on the second roll... and so on. But that's a lot of math.

The probability of an event (death) and its complement (not death) totals 1.0. So one way we can get the probability of death is 1.0 - the probability of life.

Okay, so the only way you'll live if is if survive all 100 rolls. Each dice roll is independent (surviving the first dice roll doesn't affect the second dice roll which doesn't affect the third). So each individual dice roll has probability 0.99 of survival. For joint probability, we can multiply these together. The probability of getting heads on a coin twice is 0.5 * 0.5 = 0.25. So in our situation here, p(survival) = 0.99, and 100 times means 0.99^100, to get the probability of survival. 0.99^100 = 0.36. 36% chance of survival.

The probability of death is thus 1 - 0.36 = 0.64. 64% chance of death.

[dmos62]

Counter question. How to calculate how many tries it would take to reach a specific probability for an outcome? For example, how many times do I have to roll the dice to have 90% chance of death? Due to my field of work, I'd solve everything by bruteforce, but I wonder what a more elegant solution could be.

[mark-r]

The comment that prompted the question stated the opposite probability - 99% chance of death, not life. That changes the odds quite drastically.

[dmos62]

Clear and concise. Thanks!

[saagarjha]

The chance you don't experience it after hundred times is 0.99^100≈0.37.

[parliament32]

Right, but I'm not going to nearly-drown 50-100 times in my life. I'd definitely put this in the "not worth worrying about" category.

Being a human and doing human activities carries a certain amount of risk. If we over-analyze things we end up either being too scared to do anything interesting... and if we start applying this "I"m scared of everything" mentality to parenting we fall into the "helicopter parent" trap which is even worse.

[dmos62]

Being scared of being scared is also a thing. If water got into my loved one's lungs, I wouldn't take a 1-2% risk of them suffocating in their sleep. I only gamble with what I'm willing to lose.

[frobozz]

Drownings are rare, I would say that 1-2% of something rare is very rare.

[jakemal]

Sure. But given someone has drowned, a 1-2% of something happening should result in serious precautions being taken.

[AstralStorm]

Said serious precaution is monitoring by a person.

[remcob]

Indeed, especially considering that this is "1%-2% of all drownings". It says nothing about how many people are suffering from this after a near-drowning and subsequently recover from a near-second-drowning. For all we know more than half of the near-drownings may end up with secondary symptoms.

Also we don't know how many near-drownings vs drownings there are. Lot of good statistical quiz questions in here.