class_docstr: Test statistic holder for Wald-type tests
  
  Parameters
  ----------
  stat : float
      The test statistic
  df : int
      Degree of freedom.
  null : str
      A statement of the test's null hypothesis
  alternative : str
      A statement of the test's alternative hypothesis
  name : str, default "" (empty)
      Name of test
docstr: Critical values test for common test sizes
code: def critical_values(self) -> dict[str, float]:
      """Critical values test for common test sizes"""
      return dict(
          zip(["10%", "5%", "1%"], self.dist.ppf([0.9, 0.95, 0.99]))
      )
  
file_path: arch/arch/utility/testing.py
imports: from __future__ import annotations
  from functools import cached_property
  from scipy.stats import chi2
label_desc: Use image node_id 4 for calling the WaldTestStatistic obj's underlying member method code with example usage: obj.critical_values() and returns: dict