Table of Chi-2 values given confidence and degree of freedom

chi2table.ipynb

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      "source": [
        "# $\\chi^{2}$ Distribution\n",
        "This notebook provides credible levels for a $\\chi^{2}$ distribution. Adapted from http://www.reid.ai/2012/09/chi-squared-distribution-table-with.html. Note that only for dof=1, 1sigma corresponds to 68.3.\n"
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      "source": [
        "import numpy as np\n",
        "from scipy.stats import chi2"
      ]
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      "source": [
        "sigmas = [1.0, 2.0, 3.0, 4.0]                       # standard deviations\n",
        "confs = [chi2.cdf(s*s, 1) for s in sigmas] # confidence intervals for k=1\n",
        "\n",
        "\n",
        "print('Confidence \\t'+'\\t'.join([\"{:8.2f}%\".format(c*100) for c in confs]))\n",
        "print('p-value    \\t'+'\\t'.join([\"{:8.5f}\".format(1.-c) for c in confs]))\n",
        "print('sigma(k=1) \\t'+'\\t'.join([\"{:8.2f}\".format(s) for s in sigmas]))\n",
        "\n",
        "dof = np.arange(1, 11)\n",
        "\n",
        "print(73*'-')\n",
        "for d in dof:\n",
        "  chi2s = [chi2.ppf(c, d) for c in confs]\n",
        "  print('chi2(d=%d) \\t'%d+'\\t'.join(['%8.2f'%ch for ch in chi2s]))\n"
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          "text": [
            "Confidence \t   68.27%\t   95.45%\t   99.73%\t   99.99%\n",
            "p-value    \t 0.31731\t 0.04550\t 0.00270\t 0.00006\n",
            "sigma(k=1) \t    1.00\t    2.00\t    3.00\t    4.00\n",
            "-------------------------------------------------------------------------\n",
            "chi2(d=1) \t    1.00\t    4.00\t    9.00\t   16.00\n",
            "chi2(d=2) \t    2.30\t    6.18\t   11.83\t   19.33\n",
            "chi2(d=3) \t    3.53\t    8.02\t   14.16\t   22.06\n",
            "chi2(d=4) \t    4.72\t    9.72\t   16.25\t   24.50\n",
            "chi2(d=5) \t    5.89\t   11.31\t   18.21\t   26.77\n",
            "chi2(d=6) \t    7.04\t   12.85\t   20.06\t   28.91\n",
            "chi2(d=7) \t    8.18\t   14.34\t   21.85\t   30.96\n",
            "chi2(d=8) \t    9.30\t   15.79\t   23.57\t   32.93\n",
            "chi2(d=9) \t   10.42\t   17.21\t   25.26\t   34.85\n",
            "chi2(d=10) \t   11.54\t   18.61\t   26.90\t   36.72\n"
          ]
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      ]
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