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Last modified: December 2013

URL: http://cxc.harvard.edu/sherpa/ahelp/chi2xspecvar.html
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AHELP for CIAO 4.6 Sherpa v2

chi2xspecvar

Context: statistics

Synopsis

Chi-square statistic with variance computed from data amplitudes.

Description

The chi2xspecvar statistic is equivalent to chi2datavar ("ahelp chi2datavar"), except that when the number of counts in a channel bin is less than 1, the variance is set to 1.

Example

sherpa> set_stat("chi2xspecvar")
sherpa> show_stat()
Statistic: Chi2XspecVar

Set the fitting statistic and then confirm the new value.

Bugs

See the bugs pages on the Sherpa website for an up-to-date listing of known bugs.

See Also

info
list_stats
statistics
cash, chi2constvar, chi2datavar, chi2gehrels, chi2modvar, chisquare, cstat, get_prior, leastsq, list_priors, set_prior, set_sampler, set_stat

Last modified: December 2013
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