Comments on: A Confession from a former “keV” Junkie: 1. It’s a Plague. http://hea-www.harvard.edu/AstroStat/slog/2008/a-confession-from-a-former-kev-junkie-1-its-a-plague/ Weaving together Astronomy+Statistics+Computer Science+Engineering+Intrumentation, far beyond the growing borders Fri, 01 Jun 2012 18:47:52 +0000 hourly 1 http://wordpress.org/?v=3.4 By: vlk http://hea-www.harvard.edu/AstroStat/slog/2008/a-confession-from-a-former-kev-junkie-1-its-a-plague/comment-page-1/#comment-323 vlk Thu, 11 Sep 2008 14:40:37 +0000 http://hea-www.harvard.edu/AstroStat/slog/?p=644#comment-323 They are not always scale or shift invariant (e.g., wavelength vs energy, flux vs magnitude, events vs binned counts, etc). btw, there seem to be some rather persistent comment problems. I keep getting error messages saying I am posting spam. The only way to get rid of it seems to be to first write the comment, copy the text of the comment (ctrl/cmd-C), reload the page, paste the text (ctrl/cmd-V), and then hit submit. They are not always scale or shift invariant (e.g., wavelength vs energy, flux vs magnitude, events vs binned counts, etc).

btw, there seem to be some rather persistent comment problems. I keep getting error messages saying I am posting spam. The only way to get rid of it seems to be to first write the comment, copy the text of the comment (ctrl/cmd-C), reload the page, paste the text (ctrl/cmd-V), and then hit submit.

]]> By: hlee http://hea-www.harvard.edu/AstroStat/slog/2008/a-confession-from-a-former-kev-junkie-1-its-a-plague/comment-page-1/#comment-322 hlee Wed, 10 Sep 2008 13:59:27 +0000 http://hea-www.harvard.edu/AstroStat/slog/?p=644#comment-322 As long as these ambiguous/convenient units and their ambiguous/convenient transformations are shift invariant or scale invariant or both (WLOG), same statistics thrive. People still live after the tower of Babel. We need good translators, though. As long as these ambiguous/convenient units and their ambiguous/convenient transformations are shift invariant or scale invariant or both (WLOG), same statistics thrive. People still live after the tower of Babel. We need good translators, though.

]]> By: vlk http://hea-www.harvard.edu/AstroStat/slog/2008/a-confession-from-a-former-kev-junkie-1-its-a-plague/comment-page-1/#comment-321 vlk Wed, 10 Sep 2008 12:01:47 +0000 http://hea-www.harvard.edu/AstroStat/slog/?p=644#comment-321 You make a good point, Jaesub. We do tend to use units where the physically interesting range seems to always go from around a few hundredths to a few hundreds. Anything beyond, and somebody invents a new measure. This is why interplanetary distances are listed in A.U., coronal heights in RStar, interstellar distances in pc, intergalactic distances in Mpc, and so on. The few apparent exceptions, like the H column density NH (which is usually around 1e20 cm^-2), upon further inspection turn out to be "correctly normalized" (because in this case absorption cross-section is around 1e-22 cm^2 and it is the product of the two that is the interesting quantity). You make a good point, Jaesub. We do tend to use units where the physically interesting range seems to always go from around a few hundredths to a few hundreds. Anything beyond, and somebody invents a new measure. This is why interplanetary distances are listed in A.U., coronal heights in RStar, interstellar distances in pc, intergalactic distances in Mpc, and so on. The few apparent exceptions, like the H column density NH (which is usually around 1e20 cm^-2), upon further inspection turn out to be “correctly normalized” (because in this case absorption cross-section is around 1e-22 cm^2 and it is the product of the two that is the interesting quantity).

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