# Prevalence threshold (ϕe) and the geometry of screening curves

@article{Balayla2020PrevalenceT,
title={Prevalence threshold (ϕe) and the geometry of screening curves},
author={Jacques Balayla},
journal={PLoS ONE},
year={2020},
volume={15}
}
• J. Balayla
• Published 31 May 2020
• Medicine, Mathematics, Physics
• PLoS ONE
The relationship between a screening tests’ positive predictive value, ρ, and its target prevalence, ϕ, is proportional—though not linear in all but a special case. In consequence, there is a point of local extrema of curvature defined only as a function of the sensitivity a and specificity b beyond which the rate of change of a test’s ρ drops precipitously relative to ϕ. Herein, we show the mathematical model exploring this phenomenon and define the prevalence threshold (ϕe) point where this… Expand
14 Citations

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