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Even after you explain it, I can barely grasp the significance. Given the expected level of understanding of someone reading a BBC article about this topic, I d

Even after you explain it, I can barely grasp the significance. Given the expected level of understanding of someone reading a BBC article about this topic, I don't think they are wrong at all in explaining it that way - that is, I don't think their intended audience would take the message differently to any extent whatsoever if they had explained the way you do. To be more specific, to the average BBC reader, the phrases The measurement from LHCb is three-sigma - meaning there is roughly a one in 1,000 chance that the measurement is a statistical coincidence. and The measurement from LHCb is three-sigma - meaning there is roughly a one in 1,000 chance to have seen this data even if the particle doesn't exist. convey the exact same message, the first one just uses fewer words.

DavidSJ 6y ago
Look, that may be so, but if it is, then they should either omit such a line entirely so as not to mislead their readers, select better language so that we don't collapse concepts which are fundamentally, completely, different from each other, or they could try to educate the public on a distinction which is fundamental to science. I mean, we might as well say that the BBC should just use the words "million" and "billion" interchangeably because most readers have no sense of scale. Bottom line: thanks to this line, the reader is likely to think that new physics has very likely been discovered, when the opposite is the case.
- simiones 6y ago
  I don't agree. The whole paragraph makes that clear - 1 in 1000 is actually pretty good odds that this is just a coincidence, and most people should know this intuitively. > The measurement from LHCb is three-sigma - meaning there is roughly a one in 1,000 chance that the measurement is a statistical coincidence. So people should not get carried away by these findings, according to team leader Prof Chris Parkes, from the University of Manchester.
davrosthedalek 6y ago
The problem with it is that layman people believe that both of these statements are equal to "it's a 999/1000 chance that it was something else". Which is not true. The difference in these two formulations is that for b) it's explicit wrong, for a) this is arguably what the article says (which is not what the scientists say)
- simiones 6y ago
  The article can be read as "there is a 999/1000 chance that this is not a coincidence". This is strictly speaking correct, because it doesn't specify what the coincidence would be. The correct interpretation is "there is a 999/1000 chance that you wouldn't see this data if the particle didn't exist" / "there is a 1/1000 chance that you would see this data if the particle didn't exist". The wrong interpretation that still agrees with the statement is "there is a 999/1000 chance that the particle exists given that we have seen this data" / "there is a 1/1000 chance that the particle doesn't exist given that we have seen this data". P(data | no particle) = P (no particle | data) * P (data) / P (no particle). As a layman, I have no idea what P(data) is, and I think no one can give a convincing estimate for P(no particle). Since P(data | no particle) and P(no particle | data) are in fact proportional, the only thing I should really care about as a layman is the value of any one of them. I any way can't evaluate myself what would be a convincing probability, since I don't have any proper priors.
  - davrosthedalek 6y ago
    No, not quite. The probability that this is not a coincidence is unknown. The probability that you SAW the data if the particle didn't exist is 100%. The probability that you will not see it /again/ is 999/1000. The probabilities 1/1000 (or 999/1000) are only meaningul probabilites for something in the world where in fact it was a coincidence. In any other world, they are not. So saying "there is a 999/1000 chance that this is not a coincidence" isn't true, as the calculation of 999/1000 must assume that it fact it IS a coincidence.

DavidSJ 6y ago

Look, that may be so, but if it is, then they should either omit such a line entirely so as not to mislead their readers, select better language so that we don't collapse concepts which are fundamentally, completely, different from each other, or they could try to educate the public on a distinction which is fundamental to science. I mean, we might as well say that the BBC should just use the words "million" and "billion" interchangeably because most readers have no sense of scale. Bottom line: thanks to this line, the reader is likely to think that new physics has very likely been discovered, when the opposite is the case.

simiones 6y ago
I don't agree. The whole paragraph makes that clear - 1 in 1000 is actually pretty good odds that this is just a coincidence, and most people should know this intuitively. > The measurement from LHCb is three-sigma - meaning there is roughly a one in 1,000 chance that the measurement is a statistical coincidence. So people should not get carried away by these findings, according to team leader Prof Chris Parkes, from the University of Manchester.

davrosthedalek 6y ago

The problem with it is that layman people believe that both of these statements are equal to "it's a 999/1000 chance that it was something else". Which is not true. The difference in these two formulations is that for b) it's explicit wrong, for a) this is arguably what the article says (which is not what the scientists say)

simiones 6y ago
The article can be read as "there is a 999/1000 chance that this is not a coincidence". This is strictly speaking correct, because it doesn't specify what the coincidence would be. The correct interpretation is "there is a 999/1000 chance that you wouldn't see this data if the particle didn't exist" / "there is a 1/1000 chance that you would see this data if the particle didn't exist". The wrong interpretation that still agrees with the statement is "there is a 999/1000 chance that the particle exists given that we have seen this data" / "there is a 1/1000 chance that the particle doesn't exist given that we have seen this data". P(data | no particle) = P (no particle | data) * P (data) / P (no particle). As a layman, I have no idea what P(data) is, and I think no one can give a convincing estimate for P(no particle). Since P(data | no particle) and P(no particle | data) are in fact proportional, the only thing I should really care about as a layman is the value of any one of them. I any way can't evaluate myself what would be a convincing probability, since I don't have any proper priors.
- davrosthedalek 6y ago
  No, not quite. The probability that this is not a coincidence is unknown. The probability that you SAW the data if the particle didn't exist is 100%. The probability that you will not see it /again/ is 999/1000. The probabilities 1/1000 (or 999/1000) are only meaningul probabilites for something in the world where in fact it was a coincidence. In any other world, they are not. So saying "there is a 999/1000 chance that this is not a coincidence" isn't true, as the calculation of 999/1000 must assume that it fact it IS a coincidence.