list_stats

Synopsis

List all Sherpa fit statistics.

list_stats()

Description

Sherpa includes several different fit statistics that can be used to evaluate how well a model fits a data set. This function lists all statistics, by name; it accepts no arguments.

Available statistics include

• leastsq: least-squares fitting (chi-square without statistical errors)
• chi2constvar: chi-square with constant variance computed from the counts data.
• chi2modvar: chi-square with model amplitude variance.
• chi2gehrels: chi-square with gehrels method (Sherpa default).
• chi2datavar: chi-square with data variance.
• chi2xspecvar: chi-square with data variance (XSPEC-style, variance = 1.0 if data less than or equal to 0.0).
• cstat: a maximum likelihood function (XSPEC implementation of Cash)
• cash: a maximum likelihood function.

Example

sherpa> list_stats()

['leastsq', 'chi2constvar', 'chi2modvar', 'cash', 'chi2gehrels', 'chi2datavar', 'chi2xspecvar', 'cstat']

This function returns a list of all Sherpa fit statistics, by name.

Bugs

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

See Also

confidence

get_conf, get_covar, get_int_proj, get_int_unc, get_proj, get_reg_proj, get_reg_unc

contrib

get_chart_spectrum

data

get_areascal, get_arf, get_arf_plot, get_axes, get_backscal, get_bkg, get_bkg_plot, get_bkg_scale, get_coord, get_counts, get_data, get_data_plot, get_dep, get_dims, get_error, get_exposure, get_grouping, get_indep, get_quality, get_rmf, get_specresp, get_staterror, get_syserror

filtering

get_filter

fitting

calc_stat_info, get_fit, get_stat_info

info

get_default_id

methods

get_draws, get_iter_method_name, get_iter_method_opt, get_method

modeling

get_model, get_model_component, get_model_component_image, get_model_component_plot, get_model_plot, get_num_par, get_order_plot, get_par, get_pileup_model, get_response, get_source, get_source_component_image, get_source_component_plot, image_source

plotting

get_split_plot

psfs

get_kernel, get_psf

statistics

cash, chi2constvar, chi2datavar, chi2gehrels, chi2modvar, chi2xspecvar, chisquare, cstat, get_chisqr_plot, get_delchi_plot, get_prior, get_sampler, get_stat, leastsq, list_priors, set_prior, set_sampler, set_stat

utilities

get_analysis, get_rate

visualization

get_ratio, get_resid, image_getregion