Last modified: December 2020

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

calc_stat

Context: utilities

Synopsis

Calculate the fit statistic for a data set.

Syntax

calc_stat(id=None, *otherids)

id - int or str, optional
*otherids - int or str, optional

Description

Evaluate the model for one or more data sets, compare it to the data using the current statistic, and return the value. No fitting is done, as the current model parameter, and any filters, are used.


Examples

Example 1

Calculate the statistic for the model and data in the default data set:

>>> stat = calc_stat()

Example 2

Find the statistic for data set 3:

>>> stat = calc_stat(3)

Example 3

When fitting to multiple data sets, you can get the contribution to the total fit statistic from only one data set, or from several by listing the datasets explicitly. The following finds the contribution from the data sets labelled "core" and "jet":

>>> stat = calc_stat("core", "jet")

Example 4

Calculate the statistic value using two different statistics:

>>> set_stat('cash')
>>> s1 = calc_stat()
>>> set_stat('cstat')
>>> s2 = calc_stat()

PARAMETERS

The parameters for this function are:

Parameter Definition
id The data set that provides the data. If not given then all data sets with an associated model are used simultaneously.
*otherids Other data sets to use in the calculation.

Return value

The return value from this function is:

stat -- The current statistic value.


Bugs

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

See Also

data
get_bkg_chisqr_plot, get_bkg_delchi_plot, get_bkg_fit_plot, get_bkg_model_plot, get_bkg_plot, get_bkg_ratio_plot, get_bkg_resid_plot, get_bkg_source_plot
fitting
calc_stat_info, fit, simulfit
info
list_model_ids, show_bkg_model, show_bkg_source
methods
get_iter_method_name, get_iter_method_opt, list_iter_methods, set_iter_method, set_iter_method_opt
modeling
add_model, add_user_pars, clean, create_model_component, delete_bkg_model, delete_model, delete_model_component, get_model, get_model_autoassign_func, 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_source, get_source_component_image, get_source_component_plot, get_source_contour, get_source_image, get_source_plot, get_xsabund, get_xscosmo, get_xsxsect, get_xsxset, image_model, image_model_component, image_source, image_source_component, integrate, link, load_table_model, load_template_interpolator, load_template_model, load_user_model, normal_sample, reset, save_model, save_source, set_bkg_model, set_bkg_source, set_full_model, set_model, set_model_autoassign_func, set_pileup_model, set_source, set_xsabund, set_xscosmo, set_xsxsect, set_xsxset, t_sample, uniform_sample
plotting
get_cdf_plot, get_pdf_plot, get_pvalue_plot, get_pvalue_results, plot_cdf, plot_fit, plot_fit_delchi, plot_fit_resid, plot_model, plot_model_component, plot_pdf, plot_pvalue, plot_scatter, plot_source, plot_source_component, plot_trace
psfs
delete_psf, load_conv
saving
save_delchi, save_resid
statistics
get_stat, get_stat_name, set_stat
tools
aprates, modelflux
utilities
calc_chisqr, calc_energy_flux, calc_model_sum, calc_photon_flux, calc_source_sum, eqwidth, gamma, igam, igamc, incbet, lgam
visualization
contour_model, contour_ratio, contour_resid, image_fit