5 ms·

Frustratingly, this kind of dismissal perpetuates injustices. First, let's be clear: > Doctors know that these pulse ox meters aren't very accurate and use th

by zamfi 6y ago

Frustratingly, this kind of dismissal perpetuates injustices. First, let's be clear: > Doctors know that these pulse ox meters aren't very accurate and use them accordingly Some doctors know... > Nobody's changing their plan because you have a pulse ox of 93 instead of 95. They're there to quickly measure big changes that indicate a problem. Sometimes, perhaps even often, they're used for this. It's one use case of pulse oximetry, and it's an important one. I read your post as extrapolating general claims from common cases, and erasing the real experiences of people that fall outside of these common cases. Bias often happens at the margins. That doesn't make it less real for the people who suffer from it, even if most people don't suffer, even if the common cases work well. It can be hard to see those margins when you aren't in them, but that doesn't mean they don't exist -- they are still worth writing about and trying to fix.

deleted 6y ago
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CositaS 6y ago
Also, while they might not change plan because of a reading of 93 instead of 95 - the article describes a bias of up to 8%, which does seem enough to be significant.
slowmovintarget 6y ago
This IS NOT BIAS! This is physics! As someone else pointed out, this isn't only about melanin in the skin. Darkened skin for any reason will cause this (burns, smoking, dirt, etc...). Medical personnel are trained to account for this partial accuracy. The other fact is that there are newer techniques being worked on to improve the technology.
- throwanem 6y ago
  > This IS NOT BIAS! This is physics! Bias doesn't happen in physics. Bias happens where humans and physics interact. > Medical personnel are trained to account for this Medical personnel aren't the only people who use pulse oximeters and need them to read reliably. Beyond that, this thread and the article it discusses are full of examples of why "medical personnel are trained" isn't enough of an answer here.
  - dredmorbius 6y ago
    Both measurement and social/cultural bias occur in physics: https://scholar.google.com/scholar?q="bias%20in%20physics"&btnG=Search&as_sdt=800000000001&as_sdtp=on https://scholar.google.com/scholar?q="bias%20in%20physics"&b... "Cargo Cult Science" (esp. Millikan). http://calteches.library.caltech.edu/51/2/CargoCult.htm http://calteches.library.caltech.edu/51/2/CargoCult.htm Einstein to M. Curie: https://www.brainpickings.org/2016/04/19/einstein-curie-letter/ https://www.brainpickings.org/2016/04/19/einstein-curie-lett... Planck: Science advances one funeral at a time. (See also Kuhn.) https://en.wikiquote.org/wiki/Max_Planck https://en.wikiquote.org/wiki/Max_Planck
    - throwanem 6y ago
      Yes, and the point that I'm making is that "this isn't bias, this is physics" is missing the point. Yes, the way in which varying wavelengths of light interact with varying configurations of bulk matter is a physical phenomenon, and not subject to bias. But that isn't the same as saying, as the comment to which I originally replied seemed to do, that no bias can exist in the way in which that phenomenon is interpreted by humans.
      - dredmorbius 6y ago
        I suspect instances of bias introduced by other-than cultural, social, human, and perceptual dynamics are also present.
- klyrs 6y ago
  > This IS NOT BIAS! This is physics! You sound pretty emotional, maybe tone it down and try to think objectively. Just because there's an underlying physical reason for the device to be inaccurate on a subset of the population, doesn't mean that it's fair to use that device on the impacted population. It's been accepted by the medical community, despite the additional training required to correctly use the device -- amounting to guesswork when the medical personnel remember that it's necessary. Accounting for human error, this means that affected populations will receive a lower quality of care. Just a hypothetical. Would it be accepted if it was accurate for black women, and required guesswork when treating white men? Because there is a long history of significant bias in medical studies. Just because "it's just physics" explains the device's flaw, doesn't mean that acceptance of a flawed device isn't a result of systemic bias.
  - deleted 6y ago
    [deleted]
- oivey 6y ago
  Physics describes how oxygen saturated blood looks in the infrared, but using that information in a device is engineering. The engineers who design these devices should have better understood how something obvious like skin color would bias the measurements. It seems like the physics could be exploited again via a visible light sensor that detects darker skin. This is absolutely bias, and it is entirely due to engineering choices made by people, not nature.
- dllthomas 6y ago
  When a measurement device is, in some settings, consistently off in one direction... that's one of the most central definitions of bias.
Teknoman117 6y ago
I'd hardly call it injustice. Anything based on light is going to be variable depending on skin tone (or, as other have mentioned, darkened skin for any reason). The only thing you could claim injustice for would be if there was no other mechanism for measuring blood oxygen other than something that was known to not work properly for people of color.
- zamfi 6y ago
  A lot of other folks made this point, but I’m replying here because your response was the most considered. No one — myself including — is saying that physics is biased, or that this tool is inherently biased. The headline is misleading, it’s really talking about the interpretation of the number that’s biased, not the physics. The number is just a number. The bias comes through the typical institutional use of this tool, as described in the article: the “normal” regions are based on “normal” for lightly pigmented people, so heavily pigmented people are by default not in the “normal” range. Do some doctors realize this? Of course they do. But as programmers we all know the power of defaults some doctors won’t realize this, or will forget, or will realize it but it will still affect them. Other policies (like the Medicaid one described in the article) also ignore these differences. It’s not the physics that’s biased. It’s the institutional and individual assumptions around the tool.

by zamfi 6y ago

deleted 6y ago

[deleted]

CositaS 6y ago

Also, while they might not change plan because of a reading of 93 instead of 95 - the article describes a bias of up to 8%, which does seem enough to be significant.

slowmovintarget 6y ago

This IS NOT BIAS! This is physics! As someone else pointed out, this isn't only about melanin in the skin. Darkened skin for any reason will cause this (burns, smoking, dirt, etc...). Medical personnel are trained to account for this partial accuracy. The other fact is that there are newer techniques being worked on to improve the technology.

throwanem 6y ago
> This IS NOT BIAS! This is physics! Bias doesn't happen in physics. Bias happens where humans and physics interact. > Medical personnel are trained to account for this Medical personnel aren't the only people who use pulse oximeters and need them to read reliably. Beyond that, this thread and the article it discusses are full of examples of why "medical personnel are trained" isn't enough of an answer here.
- dredmorbius 6y ago
  Both measurement and social/cultural bias occur in physics: https://scholar.google.com/scholar?q="bias%20in%20physics"&btnG=Search&as_sdt=800000000001&as_sdtp=on https://scholar.google.com/scholar?q="bias%20in%20physics"&b... "Cargo Cult Science" (esp. Millikan). http://calteches.library.caltech.edu/51/2/CargoCult.htm http://calteches.library.caltech.edu/51/2/CargoCult.htm Einstein to M. Curie: https://www.brainpickings.org/2016/04/19/einstein-curie-letter/ https://www.brainpickings.org/2016/04/19/einstein-curie-lett... Planck: Science advances one funeral at a time. (See also Kuhn.) https://en.wikiquote.org/wiki/Max_Planck https://en.wikiquote.org/wiki/Max_Planck
  - throwanem 6y ago
    Yes, and the point that I'm making is that "this isn't bias, this is physics" is missing the point. Yes, the way in which varying wavelengths of light interact with varying configurations of bulk matter is a physical phenomenon, and not subject to bias. But that isn't the same as saying, as the comment to which I originally replied seemed to do, that no bias can exist in the way in which that phenomenon is interpreted by humans.
    - dredmorbius 6y ago
      I suspect instances of bias introduced by other-than cultural, social, human, and perceptual dynamics are also present.
klyrs 6y ago
> This IS NOT BIAS! This is physics! You sound pretty emotional, maybe tone it down and try to think objectively. Just because there's an underlying physical reason for the device to be inaccurate on a subset of the population, doesn't mean that it's fair to use that device on the impacted population. It's been accepted by the medical community, despite the additional training required to correctly use the device -- amounting to guesswork when the medical personnel remember that it's necessary. Accounting for human error, this means that affected populations will receive a lower quality of care. Just a hypothetical. Would it be accepted if it was accurate for black women, and required guesswork when treating white men? Because there is a long history of significant bias in medical studies. Just because "it's just physics" explains the device's flaw, doesn't mean that acceptance of a flawed device isn't a result of systemic bias.
- deleted 6y ago
  [deleted]
oivey 6y ago
Physics describes how oxygen saturated blood looks in the infrared, but using that information in a device is engineering. The engineers who design these devices should have better understood how something obvious like skin color would bias the measurements. It seems like the physics could be exploited again via a visible light sensor that detects darker skin. This is absolutely bias, and it is entirely due to engineering choices made by people, not nature.
dllthomas 6y ago
When a measurement device is, in some settings, consistently off in one direction... that's one of the most central definitions of bias.

Teknoman117 6y ago

I'd hardly call it injustice. Anything based on light is going to be variable depending on skin tone (or, as other have mentioned, darkened skin for any reason). The only thing you could claim injustice for would be if there was no other mechanism for measuring blood oxygen other than something that was known to not work properly for people of color.

zamfi 6y ago
A lot of other folks made this point, but I’m replying here because your response was the most considered. No one — myself including — is saying that physics is biased, or that this tool is inherently biased. The headline is misleading, it’s really talking about the interpretation of the number that’s biased, not the physics. The number is just a number. The bias comes through the typical institutional use of this tool, as described in the article: the “normal” regions are based on “normal” for lightly pigmented people, so heavily pigmented people are by default not in the “normal” range. Do some doctors realize this? Of course they do. But as programmers we all know the power of defaults some doctors won’t realize this, or will forget, or will realize it but it will still affect them. Other policies (like the Medicaid one described in the article) also ignore these differences. It’s not the physics that’s biased. It’s the institutional and individual assumptions around the tool.