Commit a6e32312 authored by Amir MOHAMMADI's avatar Amir MOHAMMADI
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Explain that the thresholds might not satisfy the requested criteria

parent cb3964bd
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......@@ -164,6 +164,20 @@ calculation of the threshold:
By setting cost to 0.5 is equivalent to use
.. important::
Often, it is not numerically possible to match the requested criteria for
calculating the threshold based on the provided scores. Instead, the closest
possible threshold is returned. For example, using
:any:`bob.measure.eer_threshold` **will not** give you a threshold where
:math:`FAR == FRR`. Hence, you cannot report :math:`FAR` or :math:`FRR`
instead of :math:`EER`; you should report :math:`(FAR+FRR)/2` instead. This
is also true for :any:`bob.measure.far_threshold` and
:any:`bob.measure.frr_threshold`. The threshold returned by those functions
does not guarantee that using that threshold you will get the requested
:math:`FAR` or :math:`FRR` value. Instead, you should recalculate using
.. note::
Many functions in ``bob.measure`` have an ``is_sorted`` parameter, which defaults to ``False``, throughout.
However, these functions need sorted ``positive`` and/or ``negative`` scores.
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