5 ms·

Yeah, the use of "millions of times better" just doesn't pass the sniff test. Given that current commercial methods kill 90%+ bacteria in water, thus, nothing

by rmah 5y ago

Yeah, the use of "millions of times better" just doesn't pass the sniff test. Given that current commercial methods kill 90%+ bacteria in water, thus, nothing can be even 2x better...and makes me suspicious of any claim in the article. Hopefully it can help people in areas that are currently without clean water, but I'm not holding my breath.

TimTheTinker 5y ago
(CFU/mL of E. Coli with stored H2O2) / (CFU/mL of E. Coli with catalysts) = 10M With that in mind "millions of times better" isn't necessarily a disingenuous description. Though you might say it's somewhat misleading, since as the denominator goes to zero, the fraction goes to infinity :) It's the equivalent of saying 99.99999999% uptime is "ten million times more available" than 99.9% uptime - um, just give me the number of nines please!
mathstuf 5y ago
If you're measuring in (1-n) terms, you can be 2x better. 95% is 2x as good as 90% and 99.9% is 100x better. Not at all clear at first glance or sure that it's what they're doing here, but just something to keep in mind.
mabbo 5y ago
> Given that current commercial methods kill 90%+ bacteria in water, thus, nothing can be even 2x better That depends how you look at it. Is it 90% killed, or is it 10% survived? If it's 10% survived, then 100m times better is a system where 10/100m % survived instead.
gus_massa 5y ago
Here the 10^8 improvement means that if the commercial method kills 99% of the bacteria, this method kills 99.99999999% of them.
- deleted 5y ago
  [deleted]
- dmix 5y ago
  People need to be taught basic statistics in school.
  - gus_massa 5y ago
    I don't think this is basic statistics. I think it the correct way of reporting the improvement, but it may be confusing for someone that does not understand the usual notation in the field. Moreover, I had to look at the paper to be sure what they were reporting. (Actually, they report the log of the improvement, i.e. something like "8" that is better to put in graph to compare different methods.)
gerdesj 5y ago
If you take your 90%+ as a baseline (ie zero) then you can fiddle with the stats to get a massive number. Let's say the best effort is 91.001% and our smart new process is 92.001%. Now set the baseline at 91.000% This is the sleight of hand bit: If we say that "normal" is 91.000, we now set the best effort as 0.001 and our effort as 1.001. That can seem quite reasonable when trotted out by a news reader or reporter. So we are (1.001/0.001) x 100 = 100,100% better than the previous best! The real improvement is more like: 92.001/91.001 x 100 = 101.098% which is a bit obvious when you look at the numbers involved. With a single quite clumsy move and a bit of misdirection you can turn 101 into 100,100 and sound quite convincing. Now that's only using the very basic arithmetic operations and a bit of bullshit. The clever kids can really go to town. We need some sort of laws about the presentation of statistics because it really is getting out of hand. The nonsense I've just presented isn't fiction. I saw something similar recently, can't remember what for but it took a while for me to calm down afterwards 8)
- epivosism 5y ago
  Agree we need to be rigorous about this. But in your example it's more sane if you flip it. Survival rate from a new medicine may be 99.99% and only allows 1.0001 multiple of improvement. For severe outcomes, not allowing expansive language to describe improvements is a legitimate problem. i.e. if we insisted on this, it would be hard to motivate improvements in safety from 99% to 99.999% since they are "only <1% improvements". So in cases like this I think of it in reverse: the death rate of 0.01% can be improved by 90% (or 10x) to 0.001%. This does run the risk of inflating the importance of the fix when the base rate is extremely low. My rule is: articles which use multiples or percentages must give enough detail to exactly reconstruct the calculation method used.
- epivosism 5y ago
  And don't even get started on "Improved by 40%" (1.4x) being occasionally referred to as "Improved to 140%" (1.4x), which then is backported "Improved by 140%" (to 2.4x). The real problem is percentages; people also intuitively assume "50% less than (50% more than X) is X"
sp332 5y ago
It's comparing the needed concentrations of the disinfectant chemicals. You can use many orders of magnitude less of this than of chlorine.
permo-w 5y ago
this is poor logic. imagine two disinfectants, A and B, both kill 90%+ of known bacteria. imagine that you need 1 part per billion for A to be effective and 10 million parts per billion for B to be effective. “Better” does not necessarily mean “kills a higher percentage of bacteria” By the way, this isn’t a comment on the article itself in any way, simply a comment on the logic of your comment

by rmah 5y ago

TimTheTinker 5y ago

(CFU/mL of E. Coli with stored H2O2) / (CFU/mL of E. Coli with catalysts) = 10M With that in mind "millions of times better" isn't necessarily a disingenuous description. Though you might say it's somewhat misleading, since as the denominator goes to zero, the fraction goes to infinity :) It's the equivalent of saying 99.99999999% uptime is "ten million times more available" than 99.9% uptime - um, just give me the number of nines please!

mathstuf 5y ago

If you're measuring in (1-n) terms, you can be 2x better. 95% is 2x as good as 90% and 99.9% is 100x better. Not at all clear at first glance or sure that it's what they're doing here, but just something to keep in mind.

mabbo 5y ago

> Given that current commercial methods kill 90%+ bacteria in water, thus, nothing can be even 2x better That depends how you look at it. Is it 90% killed, or is it 10% survived? If it's 10% survived, then 100m times better is a system where 10/100m % survived instead.

gus_massa 5y ago

Here the 10^8 improvement means that if the commercial method kills 99% of the bacteria, this method kills 99.99999999% of them.

deleted 5y ago
[deleted]
dmix 5y ago
People need to be taught basic statistics in school.
- gus_massa 5y ago
  I don't think this is basic statistics. I think it the correct way of reporting the improvement, but it may be confusing for someone that does not understand the usual notation in the field. Moreover, I had to look at the paper to be sure what they were reporting. (Actually, they report the log of the improvement, i.e. something like "8" that is better to put in graph to compare different methods.)

gerdesj 5y ago

If you take your 90%+ as a baseline (ie zero) then you can fiddle with the stats to get a massive number. Let's say the best effort is 91.001% and our smart new process is 92.001%. Now set the baseline at 91.000% This is the sleight of hand bit: If we say that "normal" is 91.000, we now set the best effort as 0.001 and our effort as 1.001. That can seem quite reasonable when trotted out by a news reader or reporter. So we are (1.001/0.001) x 100 = 100,100% better than the previous best! The real improvement is more like: 92.001/91.001 x 100 = 101.098% which is a bit obvious when you look at the numbers involved. With a single quite clumsy move and a bit of misdirection you can turn 101 into 100,100 and sound quite convincing. Now that's only using the very basic arithmetic operations and a bit of bullshit. The clever kids can really go to town. We need some sort of laws about the presentation of statistics because it really is getting out of hand. The nonsense I've just presented isn't fiction. I saw something similar recently, can't remember what for but it took a while for me to calm down afterwards 8)

epivosism 5y ago
Agree we need to be rigorous about this. But in your example it's more sane if you flip it. Survival rate from a new medicine may be 99.99% and only allows 1.0001 multiple of improvement. For severe outcomes, not allowing expansive language to describe improvements is a legitimate problem. i.e. if we insisted on this, it would be hard to motivate improvements in safety from 99% to 99.999% since they are "only <1% improvements". So in cases like this I think of it in reverse: the death rate of 0.01% can be improved by 90% (or 10x) to 0.001%. This does run the risk of inflating the importance of the fix when the base rate is extremely low. My rule is: articles which use multiples or percentages must give enough detail to exactly reconstruct the calculation method used.
epivosism 5y ago
And don't even get started on "Improved by 40%" (1.4x) being occasionally referred to as "Improved to 140%" (1.4x), which then is backported "Improved by 140%" (to 2.4x). The real problem is percentages; people also intuitively assume "50% less than (50% more than X) is X"

sp332 5y ago

It's comparing the needed concentrations of the disinfectant chemicals. You can use many orders of magnitude less of this than of chlorine.

permo-w 5y ago

this is poor logic. imagine two disinfectants, A and B, both kill 90%+ of known bacteria. imagine that you need 1 part per billion for A to be effective and 10 million parts per billion for B to be effective. “Better” does not necessarily mean “kills a higher percentage of bacteria” By the way, this isn’t a comment on the article itself in any way, simply a comment on the logic of your comment