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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
by 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 agoThis 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 agoThis 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 agoOh 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[deleted]