Houston is experiencing its third ‘500-year’ flood in 3 years • Hacker News Board

Re: Houston is experiencing its third ‘500-year’ flood in 3 years

#201

Post by dragonwriter » Wed, Aug 30, 2017, 7:20 PM UTC

davrosthedalek wrote: post #199

Mz wrote: post #141

Earlier quoted context omitted.

Yes, but health insurance worked differently before Obamacare. Insurance companies simply did not cover chronically ill people or people with preexisting conditions, thus they were able to arrange a "bet." Obamacare removes the element of a "bet" from the system. Just like the government provides fire protection in the form of fire departments, the government needs to provide health care. What we are doing currently…

If I'm not mistaken, they also had yearly or life-time limits, removing the "losing" part of the betting from the system. Insurances are not bets, not more than other commercial undertakings. They are, for the insured, hedges against bets. The bet is: I will not get sick with something that will ruin me financially. Or: My house will not burn down. You pay a steady, comparably small (to the risk) amount of money. Sti…

> they also had yearly or life-time limits

Usually, both. Plus, if you had high expenses they'd actively search for an (even unrelated) pre-existing condition as a pretext to cancel your coverage (recission).

Re: Houston is experiencing its third ‘500-year’ flood in 3 years

#202

Post by oso2k » Wed, Aug 30, 2017, 7:21 PM UTC

oso2k wrote: post #74

bkohlmann wrote: post #2

While the article obliquely makes reference to this, I wonder if this is somewhat similar to the "birthday" problem in statistics. Any given person has ~1 in 365 chance of being born on a particular day. Yet, if you have 30 people in a room, there is a greater than 50 percent chance that at least one PAIR has the same birthday. Given the hundreds of cities (thousands?) in the US that may be affected by a flood, it's…

The "Birthday Problem" has a simple explanation. Something like nearly 45% of people are born in the Summer months. Ensure that you get people of different ages and your chances of finding someone with similar/same birthday goes up enormously.

For those who down voted me, you do not know your sample set or your test subjects. Go to the empirical data sources. Human behavior certainly affects the real probabilities. As of 2015 in the US [0], a person is more likely to be born in July, August or September. They're also more likely to be born during the middle of the work week rather than the weekends. Draw your own conclusions from the data.

[0] https://www.cdc.gov/nchs/data/nvsr/nvsr66/nvsr66_01_tables.p...

Re: Houston is experiencing its third ‘500-year’ flood in 3 years

#203

Post by Mz » Wed, Aug 30, 2017, 7:31 PM UTC

davrosthedalek wrote: post #199

Mz wrote: post #141

Earlier quoted context omitted.

Yes, but health insurance worked differently before Obamacare. Insurance companies simply did not cover chronically ill people or people with preexisting conditions, thus they were able to arrange a "bet." Obamacare removes the element of a "bet" from the system. Just like the government provides fire protection in the form of fire departments, the government needs to provide health care. What we are doing currently…

If I'm not mistaken, they also had yearly or life-time limits, removing the "losing" part of the betting from the system. Insurances are not bets, not more than other commercial undertakings. They are, for the insured, hedges against bets. The bet is: I will not get sick with something that will ruin me financially. Or: My house will not burn down. You pay a steady, comparably small (to the risk) amount of money. Sti…

Insurances are not bets

Origin story for Lloyd's of London:

The patrons bet, for example, on whether Admiral John Byng would be shot for his incompetence in a naval battle with the French. He was.

The gentlemen of Lloyd's would have had no qualms about taking my bet on my own life.

Edward Lloyd realised his customers were as thirsty for information to fuel their bets as they were for coffee, and began to assemble a network of informants and a newsletter full of information about foreign ports, tides, and the comings and goings of ships.

His newsletter became known as Lloyd's List.

Lloyd's coffee house hosted ship auctions, and gatherings of sea captains who would share stories.

If someone wished to insure a ship, that could be done too: a contract would be drawn up, and the insurer would sign his name underneath - hence the term "underwriter". It became hard to say quite where coffee-house gambling ended and formal insurance began.

http://www.bbc.com/news/business-38905963

https://news.ycombinator.com/item?id=13911451#13912524

Re: Houston is experiencing its third ‘500-year’ flood in 3 years

#204

Post by randcraw » Wed, Aug 30, 2017, 9:09 PM UTC

pdq wrote: post #90

mbroncano wrote: post #77

The elephant in the room has been mentioned somewhere else these days: severe lack of planning and crumbling infrastructures. Remarkably how ne of the few non-partisan issues on the table goes under the radar time and time again. Tongue in cheek, we might think only polemic issue get the attention of the public. There is also the notion of national pride. We built our infrastructural base earlier than pretty much any…

Which other city in the US can handle 40 or 50 inches of rain, and 15 trillion gallons of water, within a one week timespan? That's as much rain as most US cities get in a year. This is not the fault of poor planning or poor infrastructure in Houston. It's freak weather event that shouldn't just be given partisan rhetoric.

Similar freak weather happened 16 years ago in Houston (Allison, $5 billion in damage). It took Houston at least 5 years to recover then. It's pretty clear now that between the upgrades in water management after Allison and the addition of another 2 million residents since then, Houston wasn't as well prepared as it should be for another Allison, much less a Harvey.

In the past two consecutive years, Houston has experienced significant urban flooding due to what are now "typical" big rains. But even 1-year storm events like those were too much for the city's drainage system to handle. The city fathers must be aware that flooding has become a chronic problem.

The lesson from Katrina was that New Orleans' levees were undersized and unable to withstand overflow, leading to catastrophic flooding, and the destruction of homes not built to a modern flood-resistant design standard.

I think the lesson from Harvey was not that Houston has a severe drainage problem, but without significant upgrades, the problem is going to guarantee more ongoing and occasionally catastrophic floods in the very near future.

Re: Houston is experiencing its third ‘500-year’ flood in 3 years

#205

Post by quesera » Thu, Aug 31, 2017, 5:52 AM UTC

oso2k wrote: post #202

oso2k wrote: post #74

Earlier quoted context omitted.

The "Birthday Problem" has a simple explanation. Something like nearly 45% of people are born in the Summer months. Ensure that you get people of different ages and your chances of finding someone with similar/same birthday goes up enormously.

For those who down voted me, you do not know your sample set or your test subjects. Go to the empirical data sources. Human behavior certainly affects the real probabilities. As of 2015 in the US [0], a person is more likely to be born in July, August or September. They're also more likely to be born during the middle of the work week rather than the weekends. Draw your own conclusions from the data. [0] https://www.…

Your information is interesting, but your inference is incorrect.

The Birthday Paradox has absolutely nothing to do with procreation, and everything to do with statistical probability.

Re: Houston is experiencing its third ‘500-year’ flood in 3 years

#206

Post by kbutler » Thu, Aug 31, 2017, 11:52 AM UTC

21 wrote: post #83

kbutler wrote: post #32

Earlier quoted context omitted.

Parent means Nassim Nicholas Taleb http://www.fooledbyrandomness.com/ And yes, basically we don't understand the actual probability of a "500-year storm", so our 0.2% chance per year is unreliable at best, more likely misleading. Just like Europeans didn't know the actual probability of a black swan until they found them in Australia.

I think the idea of a black swan is something which you don't even imagine before you encounter it, ie: nobody would even think about computing the probability of a black swan (bird) existing.

While unimaginability may fit the original conception of a black swan, Taleb's book is "The Black Swan: The Impact of the Highly Improbable" (not unimaginable or inconceivable) and defines a black swan as "an outlier, as it lies outside the realm of regular expectations, because nothing in the past can convincingly point to its possibility." http://www.nytimes.com/2007/04/22/books/chapters/0422-1st-ta...

Re: Houston is experiencing its third ‘500-year’ flood in 3 years

#207

Post by Piskvorrr » Thu, Aug 31, 2017, 12:27 PM UTC

waqf wrote: post #8

bkohlmann wrote: post #2

While the article obliquely makes reference to this, I wonder if this is somewhat similar to the "birthday" problem in statistics. Any given person has ~1 in 365 chance of being born on a particular day. Yet, if you have 30 people in a room, there is a greater than 50 percent chance that at least one PAIR has the same birthday. Given the hundreds of cities (thousands?) in the US that may be affected by a flood, it's…

Good point, but the chance of a given city having a 500-year flood in three given successive years is only (0.002)³ = 8 × 10⁻⁹. So even if we allowed for 100 U.S. cities, 10 different natural disasters and 10 different three-year periods we're still talking about a probability of less than 0.01%.

...the assumption being that the risks are separate. This is clearly false - you are not rolling dice here, the probabilities of the same disaster at geographically "close" cities are linked.

Re: Houston is experiencing its third ‘500-year’ flood in 3 years

#208

Post by Piskvorrr » Thu, Aug 31, 2017, 12:31 PM UTC

dTal wrote: post #108

pixl97 wrote: post #33

Earlier quoted context omitted.

>. It would seem the probably has gone up due to climate change That probably has a small reason to do with the increase, but your next line highlights the issue. > or that we're noticing the floods more now because there's more damage to be caused to more things that have been built up No, not exactly. The more stuff you build, the faster water runs off. Unincorporated land has a pretty high water slowing capability…

Sounds like an effective, cheap solution would be water butts on every gutter.

Up to a point. To continue the bandwidth analogy, having a buffer is cheap - unless the input link fills it faster than the output link can handle, for a prolonged period. The buffer gives you some extra time for processing, but when it fills, you are back to step 1.

Re: Houston is experiencing its third ‘500-year’ flood in 3 years

#209

Post by Piskvorrr » Thu, Aug 31, 2017, 12:38 PM UTC

dsfyu404ed wrote: post #4

bkohlmann wrote: post #2

While the article obliquely makes reference to this, I wonder if this is somewhat similar to the "birthday" problem in statistics. Any given person has ~1 in 365 chance of being born on a particular day. Yet, if you have 30 people in a room, there is a greater than 50 percent chance that at least one PAIR has the same birthday. Given the hundreds of cities (thousands?) in the US that may be affected by a flood, it's…

Nobody notices the 500yr events that happen in the middle of nowhere.

With water? Unlikely. Water doesn't just drop and disappear on the same spot in the middle of nowhere, it tends to move downstream, into places that are in the middle of somewhere - as we have seen with the Mississippi watershed: first Out In Nowhere, IN, then ORCS, then Lake Ponchartrain. A 500y water event in nowhere land would still propagate; the speed of water release from the drop point (sorry for not using the correct jargon) would mean the difference between a 10y event downstream or a 500y event on the go.

Re: Houston is experiencing its third ‘500-year’ flood in 3 years

#210

Post by Piskvorrr » Thu, Aug 31, 2017, 12:41 PM UTC

walshemj wrote: post #177

walshemj wrote: post #20

Earlier quoted context omitted.

its the gamblers fallacy black 17 has not come up for ages so its more likely to come up - looks like the journalist does not understand probability

really voted down for pointing out probability 101 I would have expected better mathematical knowledge on HN

Probability 101 begins with a qualifier: "Assuming independent events..."

This can mean two things: a) a set of events that is evidently possible, but increasingly improbable b) events that are not independent