Fetching the Goodness of Fit

The Goodness of Fit is evaluated for the target source region using get_ts_target and get_goodness_of_fit_stats.

The different Fit Statistic function used for the different types of Datasets input are mentioned in the Gammapy documentation and are:

1. cash

   Used for dataset containing Poisson data with background model.

2. wstat

   Used for dataset containing Poisson data with background measurement.

3. chi2

   Used for FluxPointsDataset read from a file like in a Gammapy example where the pre-computed flux points are used to perform the likelihood fit, when no convolution with IRFs are needed.

get_ts_target uses the above Fit Statistic functions, to get the test statistic for the best fit and the max fit for the target source region in the provided joint datasets object.

For more general information follow the Gammapy documentation