On Apr 30, 2014, at 11:48 AM, Joey Neilsen <neilsenj_at_email.domain.hidden > It looks like dmgroup adds the errors of the grouped bins in quadrature. I believe ISIS defaults to Poisson errors upon rebinning. If you do: > > set_rebin_error_method(1,"quadsum"); > rebin_data(1,25); > > and set the fit parameters to your best fit in XSPEC, do you get the same chi^2 in ISIS? And for the unbinned HETG files, we default to the Gehrels chi^2 statistic == 1 + sqrt(counts+0.75) ~ 1.866 for all the 0 counts channels. So, that definitely increases the size of the error bars for the XSPEC case. I think that's the solution, at least for ISIS. You will definitely want to shrink those error bars for XSPEC. -Mike ---- You received this message because you are subscribed to the isis-users list. To unsubscribe, send a message to isis-users-request_at_email.domain.hiddenwith the first line of the message as: unsubscribeReceived on Wed Apr 30 2014 - 12:08:07 EDT
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