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Talk:Significance of E. Coli Evolution Experiments (view source)
Revision as of 16:36, March 25, 2009
, 16:36, March 25, 2009resp to SJohnson
:::::What do you get for the experiment two p-value using the method from the paper and at least ten million realizations? [[User:SJohnson|SJohnson]] 08:48, 25 March 2009 (EDT)
:::::What do you get for the experiment two p-value using the method from the paper and at least ten million realizations? [[User:SJohnson|SJohnson]] 08:48, 25 March 2009 (EDT)
::::::For the second replay experiment, Blount reports that one million resamplings gives a p-value of 0.0007. When I run the Monte Carlo simulations, ten million resamplings give a p-value of 0.00060; one hundred million resamplings give a p-value of 0.00062, and one ''billion'' resamplings give a p of 0.00061.
::::::As to the brute-force method for the second replay: the 4.41x10^12 combinations of five cultures picked from 340 actually represents 'only' 36.8 billion unique combinations, since for the purposes of calculating a mean generation value, the ordering of the cultures does not matter: 0, 0, 0, 0, 10 gives the same mean as 10, 0, 0, 0, 0 and 0, 10, 0, 0, 0. With brute force, it turns out that out of the 36,760,655,568 unique combinations possible in the second replay, 22,536,306 have means that are greater than or equal to 32,100.
::::::22,536,306 / 36,760,655,568 = 0.000613 = the ''exact'' p-value derived from exhaustive evaluation rather than Monte Carlo.
::::::The third replay has 9.27 x 10^22 unique combinations; at a billion comparisons a minute it would take over 170,000,000 years to check them all.--[[User:ElyM|ElyM]] 12:36, 25 March 2009 (EDT)
::::My intention is not to get caught up in a digression about Monte Carlo, though - I'd rather keep the focus on the fact that the main article should acknowledge that SJohnson is using chi-square in a way that violates accepted guidelines; this remains true whether Blount's analysis is valid or not.--[[User:ElyM|ElyM]] 12:13, 23 March 2009 (EDT)
::::My intention is not to get caught up in a digression about Monte Carlo, though - I'd rather keep the focus on the fact that the main article should acknowledge that SJohnson is using chi-square in a way that violates accepted guidelines; this remains true whether Blount's analysis is valid or not.--[[User:ElyM|ElyM]] 12:13, 23 March 2009 (EDT)