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Figure 1 | Emerging Themes in Epidemiology

Figure 1

From: Simpson's Paradox, Lord's Paradox, and Suppression Effects are the same phenomenon – the reversal paradox

Figure 1

Causal models expressed as directed acyclic graphs for possible relationships between the three observed variables: birth weight (BW), current body weight (CW) and systolic blood pressure (BP). UC is an unobserved variable that affects both BW and CW. In Figure 1d, there is a back-door path from BP to BW via CW and UC, so the association between BP and BW is therefore biased. The adjustment of CW can block the backdoor path from BP to BW via UC.

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