Prevalence Threshold and bounds in the Accuracy of Binary Classification
Systems
- URL: http://arxiv.org/abs/2112.13289v1
- Date: Sat, 25 Dec 2021 21:22:32 GMT
- Title: Prevalence Threshold and bounds in the Accuracy of Binary Classification
Systems
- Authors: Jacques Balayla
- Abstract summary: We show that relative to a perfect accuracy of 1, the positive prevalence threshold ($phi_e$) is a critical point of maximum curvature in the precision-prevalence curve.
Though applications are numerous, the ideas herein discussed may be used in computational complexity theory, artificial intelligence, and medical screening.
- Score: 0.0
- License: http://creativecommons.org/licenses/by/4.0/
- Abstract: The accuracy of binary classification systems is defined as the proportion of
correct predictions - both positive and negative - made by a classification
model or computational algorithm. A value between 0 (no accuracy) and 1
(perfect accuracy), the accuracy of a classification model is dependent on
several factors, notably: the classification rule or algorithm used, the
intrinsic characteristics of the tool used to do the classification, and the
relative frequency of the elements being classified. Several accuracy metrics
exist, each with its own advantages in different classification scenarios. In
this manuscript, we show that relative to a perfect accuracy of 1, the positive
prevalence threshold ($\phi_e$), a critical point of maximum curvature in the
precision-prevalence curve, bounds the $F{_{\beta}}$ score between 1 and
1.8/1.5/1.2 for $\beta$ values of 0.5/1.0/2.0, respectively; the $F_1$ score
between 1 and 1.5, and the Fowlkes-Mallows Index (FM) between 1 and $\sqrt{2}
\approx 1.414$. We likewise describe a novel $negative$ prevalence threshold
($\phi_n$), the level of sharpest curvature for the negative predictive
value-prevalence curve, such that $\phi_n$ $>$ $\phi_e$. The area between both
these thresholds bounds the Matthews Correlation Coefficient (MCC) between
$\sqrt{2}/2$ and $\sqrt{2}$. Conversely, the ratio of the maximum possible
accuracy to that at any point below the prevalence threshold, $\phi_e$, goes to
infinity with decreasing prevalence. Though applications are numerous, the
ideas herein discussed may be used in computational complexity theory,
artificial intelligence, and medical screening, amongst others. Where
computational time is a limiting resource, attaining the prevalence threshold
in binary classification systems may be sufficient to yield levels of accuracy
comparable to that under maximum prevalence.
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