In a causal diagram, an effect is a variable that is influenced by other cause variables. An effect is often called a descendant.

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- Ancestors
- Descendants
- Children
- Parents

Types of relations in a Causal Diagram

Staplin, N., Herrington, W. G., Judge, P. K., Reith, C. A., Haynes, R., Landray, M. J., ... & Emberson, J. (2017). Use of causal diagrams to inform the design and interpretation of observational studies: an example from the Study of Heart and Renal Protection (SHARP). Clinical Journal of the American Society of Nephrology, 12(3), 546-552.

Use of Causal Diagrams to Inform the Design and Interpretation of Observational Studies: An Example from the Study of Heart and Renal Protection (SHARP)

Each node is connected to one or more other nodes that it has a causal influence on with arrows. The arrowheads show the direction of causality.
In the diagram below, E is a descendant of A, B and D. A and D are indirect causes so they are ancestors of E. B is a parent of E and E is the child of B because B is a direct cause of E. Similarly, C is a child of E and B as it is their direct descendant and E and B are parents of C. 
A and D are only ancestors  of C but not parents and C is only a descendent and not a child of A and D because A and D are indirect causes of C and C is an indirect effect of A and D.

Example of types of relations in a causal diagram

In a causal diagram, if a cause is a direct cause of other variables, it is called a parent.

Parent relationship

In a causal diagram, a cause is a variable that influences other variables. A cause is often called an ancestor.

Ancestor relationship

In a causal diagram, if an effect is a direct effect of cause varibles, it is called a child.

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