Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optimal sampling ratios in comparative diagnostic trials   In this paper we focus on comparative diagnostic trials which are frequently
employed to compare two markers with continuous or ordinal results. We derive
explicit expressions for the optimal sampling ratio based on a common variance
structure shared by existing summary statistics of the receiver operating
characteristic (ROC) curve. Estimating the optimal ratio requires either pilot
data or parametric model assumptions; however, pilot data are often unavailable
at the planning stage of diagnostic trials. In the absence of pilot data, some
distributions have to be assumed for carrying out the calculation. An optimal
ratio from an incorrect distributional assumption may lead to an underpowered
study. We propose a two-stage procedure to adaptively estimate the optimal
ratio in comparative diagnostic trials without pilot data or assuming
parametric distributions. We illustrate the properties of the proposed method
through theoretical proofs and extensive simulation studies. We use an example
in cancer diagnostic studies to illustrate the application of our method. We
find that our method increases the power, or reduces the required overall
sample size dramatically.

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The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
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The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
20
The categories of this paper are: acc-phys
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The categories of this paper are: hep-ex
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th