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. Author manuscript; available in PMC: 2010 Jan 1.
Published in final edited form as: J Korean Stat Soc. 2009;38(1):1–10. doi: 10.1016/j.jkss.2008.10.006

Figure 1.

Figure 1

Forty causal structures among one disease gene G and three traits Y1, Y2 and Y3 that are illustrated by DAGs. The arrows from G to Yj and from Yk to Yj represent that there exist direct effects of G on Yj and Yk on Yj for j, k = 1, 2, 3. The locations of Y1, Y2 and Y3 can be exchanged arbitrarily in each structure.