Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Educational Note: Paradoxical Collider Effect in the Analysis of
  Non-Communicable Disease Epidemiological Data: a reproducible illustration
  and web application   Classical epidemiology has focused on the control of confounding but it is
only recently that epidemiologists have started to focus on the bias produced
by colliders. A collider for a certain pair of variables (e.g., an outcome Y
and an exposure A) is a third variable (C) that is caused by both. In a
directed acyclic graph (DAG), a collider is the variable in the middle of an
inverted fork (i.e., the variable C in A -> C <- Y). Controlling for, or
conditioning an analysis on a collider (i.e., through stratification or
regression) can introduce a spurious association between its causes. This
potentially explains many paradoxical findings in the medical literature, where
established risk factors for a particular outcome appear protective. We use an
example from non-communicable disease epidemiology to contextualize and explain
the effect of conditioning on a collider. We generate a dataset with 1,000
observations and run Monte-Carlo simulations to estimate the effect of 24-hour
dietary sodium intake on systolic blood pressure, controlling for age, which
acts as a confounder, and 24-hour urinary protein excretion, which acts as a
collider. We illustrate how adding a collider to a regression model introduces
bias. Thus, to prevent paradoxical associations, epidemiologists estimating
causal effects should be wary of conditioning on colliders. We provide R-code
in easy-to-read boxes throughout the manuscript and a GitHub repository
(https://github.com/migariane/ColliderApp) for the reader to reproduce our
example. We also provide an educational web application allowing real-time
interaction to visualize the paradoxical effect of conditioning on a collider
http://watzilei.com/shiny/collider/.

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The categories of this paper are: eess
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The categories of this paper are: plasm-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: cs
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The categories of this paper are: hep-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: supr-con
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The categories of this paper are: funct-an
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The categories of this paper are: math-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: acc-phys
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The categories of this paper are: alg-geom
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The categories of this paper are: bayes-an