Last modified: December 2020

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

get_pvalue_plot

Context: plotting

Synopsis

Return the data used by plot_pvalue.

Syntax

get_pvalue_plot(null_model=None, alt_model=None, conv_model=None, id=1,
otherids=(), num=500, bins=25, numcores=None, recalc=False)

conv_model - optional
id - int or str, optional
otherids - sequence of int or str, optional
num - int, optional
bins - int, optional
numcores - optional
recalc - bool, optional

Description

Access the data arrays and preferences defining the histogram plot produced by the `plot_pvalue` function, a histogram of the likelihood ratios comparing fits of the null model to fits of the alternative model using faked data with Poisson noise. Data returned includes the likelihood ratio computed using the observed data, and the p-value, used to reject or accept the null model.


Examples

Example 1

Return the values from the last call to `plot_pvalue` :

>>> pvals = get_pvalue_plot()
>>> pvals.ppp
0.472

Example 2

Run 500 simulations for the two models and print the results:

>>> pvals = get_pvalue_plot(mdl1, mdl2, recalc=True, num=500)
>>> print(pvals)

PARAMETERS

The parameters for this function are:

Parameter Definition
null_model The model expression for the null hypothesis.
alt_model The model expression for the alternative hypothesis.
conv_model An expression used to modify the model so that it can be compared to the data (e.g. a PSF or PHA response).
id The data set that provides the data. The default is 1.
otherids Other data sets to use in the calculation.
num The number of simulations to run. The default is 500.
bins The number of bins to use to create the histogram. The default is 25.
numcores The number of CPU cores to use. The default is to use all the cores on the machine.
recalc The default value ( False ) means that the results from the last call to `plot_pvalue` or `get_pvalue_plot` are returned. If True , the values are re-calculated.

Bugs

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

See Also

contrib
get_data_prof, get_data_prof_prefs, get_delchi_prof, get_delchi_prof_prefs, get_fit_prof, get_model_prof, get_model_prof_prefs, get_resid_prof, get_resid_prof_prefs, get_source_prof, get_source_prof_prefs, plot_chart_spectrum, plot_marx_spectrum, prof_data, prof_delchi, prof_fit, prof_fit_delchi, prof_fit_resid, prof_model, prof_resid, prof_source
data
get_arf_plot, 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
info
list_model_ids, show_bkg_model, show_bkg_source
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_energy_flux_hist, get_pdf_plot, get_photon_flux_hist, get_pvalue_results, get_split_plot, plot, plot_arf, plot_bkg, plot_bkg_chisqr, plot_bkg_delchi, plot_bkg_fit, plot_bkg_fit_delchi, plot_bkg_fit_resid, plot_bkg_model, plot_bkg_ratio, plot_bkg_resid, plot_bkg_source, plot_cdf, plot_chisqr, plot_data, plot_delchi, plot_energy_flux, plot_fit, plot_fit_delchi, plot_fit_resid, plot_model, plot_model_component, plot_order, plot_pdf, plot_photon_flux, plot_pvalue, plot_ratio, plot_resid, plot_scatter, plot_source, plot_source_component, plot_trace, set_xlinear, set_xlog, set_ylinear, set_ylog
psfs
delete_psf, load_conv, plot_kernel
saving
save_delchi, save_resid
statistics
get_chisqr_plot, get_delchi_plot
utilities
calc_chisqr, calc_energy_flux, calc_model_sum, calc_photon_flux, calc_source_sum, calc_stat, eqwidth
visualization
contour_model, contour_ratio, contour_resid