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From the paper: "shows our estimate that there is only a 0.5% chance that the observed retreat of Kaskawulsh Glacier happened in the absence of a climate trend

by acover 10y ago

From the paper: "shows our estimate that there is only a 0.5% chance that the observed retreat of Kaskawulsh Glacier happened in the absence of a climate trend" The 0.5% has nothing to do with the river. It is their confidence that the retreat of the glacier could occur in the absence of a climate trend based on their model.

archgoon 10y ago
Can you clarify why it is incorrect to reverse that into the statement "We estimate that there is a 99.5 percent chance that the observed retreat did not happen in the absence of a climate trend."? I confess to a fair amount of confusion at this point :) I'm sure there is something subtle (or perhaps obvious, and my brain is failing) that I'm missing. What is the properly worded complement?
- archgoon 10y ago
  This seems similar, but not identical, to the statement: If there is not a climate trend, we would expect this to happen with a .05 chance. If they meant the latter, my confusion is resolved.
  - acover 10y ago
    This is the blind leading the blind. Fundamental truth: bayes theorem. P(evidence | null hypothesis) = P(null hypothesis | evidence) * P (evidence) / P (null hypothesis) The P-value test determines: P(evidence | null hypothesis) = 0.5% = there is a 0.5% chance of the observed evidence given the null hypothesis The statement "We estimate that there is a 99.5 percent chance that the observed retreat did not happen in the absence of a climate trend." translates to P(!null hypothesis | evidence) = 99.5% By Bayes theorem: P(!null hypothesis | evidence) = P(evidence | !null hypothesis) * P (!null hypothesis) / P (evidence) We know almost none of these terms. The answer is not as simple as 99.5.
    - archgoon 10y ago
      Oh I thought we were having an interesting discussion about the linguistic mapping between probability and regular English. Sorry for wasting your time. :(
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by acover 10y ago

archgoon 10y ago

Can you clarify why it is incorrect to reverse that into the statement "We estimate that there is a 99.5 percent chance that the observed retreat did not happen in the absence of a climate trend."? I confess to a fair amount of confusion at this point :) I'm sure there is something subtle (or perhaps obvious, and my brain is failing) that I'm missing. What is the properly worded complement?

archgoon 10y ago
This seems similar, but not identical, to the statement: If there is not a climate trend, we would expect this to happen with a .05 chance. If they meant the latter, my confusion is resolved.
- acover 10y ago
  This is the blind leading the blind. Fundamental truth: bayes theorem. P(evidence | null hypothesis) = P(null hypothesis | evidence) * P (evidence) / P (null hypothesis) The P-value test determines: P(evidence | null hypothesis) = 0.5% = there is a 0.5% chance of the observed evidence given the null hypothesis The statement "We estimate that there is a 99.5 percent chance that the observed retreat did not happen in the absence of a climate trend." translates to P(!null hypothesis | evidence) = 99.5% By Bayes theorem: P(!null hypothesis | evidence) = P(evidence | !null hypothesis) * P (!null hypothesis) / P (evidence) We know almost none of these terms. The answer is not as simple as 99.5.
  - archgoon 10y ago
    Oh I thought we were having an interesting discussion about the linguistic mapping between probability and regular English. Sorry for wasting your time. :(
    - deleted 10y ago
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