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. 2014 Mar 6;43(3):922–929. doi: 10.1093/ije/dyu005

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© The Author 2014. Published by Oxford University Press on behalf of the International Epidemiological Association

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

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Figure 2. — Number of cases required in a Mendelian randomization analysis with a binary outcome and a single instrumental variable for 80% power with a 5% significance level and 1:1 ratio of cases:controls varying the size of causal effect [odds ratio per standard deviation (SD) increase in risk factor, exp(β₁)] for different values of IV strength. Left panel: = 1%–8%. Right panel: = 0.5%–3.0%

Inline graphic — Number of cases required in a Mendelian randomization analysis with a binary outcome and a single instrumental variable for 80% power with a 5% significance level and 1:1 ratio of cases:controls varying the size of causal effect [odds ratio per standard deviation (SD) increase in risk factor, exp(β₁)] for different values of IV strength. Left panel: = 1%–8%. Right panel: = 0.5%–3.0%