This paper proposes a new model to account for the "Ratio Bias." The Ratio Bias refers to phenomena wherein people form inconsistent impressions for real numbers expressed as fractions, depending on the magnitudes of absolute values appearing in numerators and denominators of the fraction. An oft-cited example in Yamagishi (1997) demonstrated that people rated cancer risk as more dangerous when it was described as "Cancer kills 1286 out of 10000 people in the population" than "24.14 out of 100." Despite the omnipresence of academic reports of ratio biases, there have been little establishments of a unified framework that could explain such results. Here, I propose a specialized version of the classic psyhophysical law, namely Weber-Fechner Law. The new model successfully accounted for the ratio bias reported in Yamagishi (1987). Possible implementation of psychological model and future directions are discussed
