A note on Youden's Jand its cost ratio

A note on Youden's J and its cost ratio

BACKGROUND The Youden index, the sum of sensitivity and specificity minus one, is an index used for setting optimal thresholds on medical tests. DISCUSSION When using this index, one implicitly uses decision theory with a ratio of misclassification costs which is equal to one minus the prevalence proportion of the disease. It is doubtful whether this cost ratio truly represents the decision m...

Ratio of Two Random Variables: A Note on the Existence of its Moments

To enable correct statistical inference, the knowledge about the existence of moments is crucial. The objective of this paper is to study the existence of the moments for the ratio Y X Z / = , where X and Y are arbitrary random variables with the additional assumption 0 ) 0 ( = = Y P . We present three existence theorems showing that specific behaviour of the distribution of Y in the neighbourh...

Sharpe Ratio Practice Note

A note on deriving weights from pairwise comparison ratio matrices

This paper addresses the Cook and Kress method regarding the use of mathematical programming to derive weights from pairwise comparison ratio matrices. We note that the Cook and Kress formulation has the shortcoming that alternative optimal solutions may occur, which would lead to an infinite set of possible weights. This paper proposes to resolve the problem by formulating a Phase II optimizat...

A note on the sex ratio in anencephalus.

While exploring the association of the sex ratio of stillbirths with cause and duration of gestation, McKeown and Lowe (1951) noted that for anencephalus sex ratio increased with duration of gestation. No explanation was offered for this observation, which is here considered briefly. In Birmingham, during the years 1940-51, 454 stillbirths and 28 infant deaths were attributed to anencephalus (4...