Last modified: December 2020

URL: https://cxc.cfa.harvard.edu/sherpa/ahelp/get_stat_info.html
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AHELP for CIAO 4.13 Sherpa v1

get_stat_info

Context: fitting

Synopsis

Return the statistic values for the current models.

Syntax

get_stat_info()

Description

Calculate the statistic value for each data set, and the combined fit, using the current set of models, parameters, and ranges.


Example

>>> res = get_stat_info()
>>> res[0].statval
498.21750663761935
>>> res[0].dof
439

PARAMETERS

This function has no parameters

Return value

The return value from this function is:

stats -- The values for each data set. If there are multiple model expressions then the last element will be the value for the combined data sets.

Notes

If a fit to a particular data set has not been made, or values - such as parameter settings, the noticed data range, or choice of statistic - have been changed since the last fit, then the results for that data set may not be meaningful and will therefore bias the results for the simultaneous results.

The return value of `get_stat_info` differs to `get_fit_results` since it includes values for each data set, individually, rather than just the combined results.

The fields of the object include:

Item Definition
name The name of the data set, or sets, as a string.
ids A sequence of the data set ids (it may be a tuple or array) included in the results.
bkg_ids A sequence of the background data set ids (it may be a tuple or array) included in the results, if any.
statname The name of the statistic function (as used in `set_stat` ).
statval The statistic value.
numpoints The number of bins used in the fits.
dof The number of degrees of freedom in the fit (the number of bins minus the number of free parameters).
qval The Q-value (probability) that one would observe the reduced statistic value, or a larger value, if the assumed model is true and the current model parameters are the true parameter values. This will be none if the value can not be calculated with the current statistic (e.g. the Cash statistic).
rstat The reduced statistic value (the statval field divided by dof ). This is not calculated for all statistics.

Bugs

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

See Also

confidence
get_conf, get_conf_results, get_covar, get_covar_opt, get_covar_results, get_covariance_results, get_int_proj, get_int_unc, get_proj, get_proj_opt, get_proj_results, get_projection_results, get_reg_proj, get_reg_unc
contrib
get_chart_spectrum, get_marx_spectrum
data
get_areascal, get_arf, get_arf_plot, get_axes, get_backscal, get_bkg, get_bkg_arf, get_bkg_chisqr_plot, get_bkg_delchi_plot, get_bkg_fit_plot, get_bkg_model, get_bkg_model_plot, get_bkg_plot, get_bkg_ratio_plot, get_bkg_resid_plot, get_bkg_rmf, get_bkg_scale, get_bkg_source, get_bkg_source_plot, get_coord, get_counts, get_data, get_data_contour, get_data_contour_prefs, get_data_image, get_data_plot, get_data_plot_prefs, 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_results
info
get_default_id, list_stats
methods
get_draws, get_iter_method_name, get_iter_method_opt, get_method, get_method_name, get_method_opt
modeling
get_model, get_model_component, get_model_component_image, get_model_component_plot, get_model_plot, get_num_par, get_num_par_frozen, get_num_par_thawed, get_order_plot, get_par, get_pileup_model, get_response, get_source, get_source_component_image, get_source_component_plot, get_source_contour, get_source_image, get_source_plot, image_source
plotting
get_split_plot
psfs
get_psf, get_psf_contour, get_psf_image, get_psf_plot
statistics
get_chisqr_plot, get_delchi_plot, get_prior, get_sampler, get_stat, get_stat_name
utilities
get_analysis, get_rate
visualization
image_getregion