A causal graphical model represents hypothesized causal relationships among variables with a graph and an accompanying probabilistic or structural model. It supports questions about what would change under an intervention, rather than merely describing correlations or predicting outcomes. section 3.2.2
Construct the graph by treating arrows as claims about direct effects. Include an arrow when a direct effect is plausible; remove one only when confident that no direct effect exists. Missing arrows therefore encode assumptions, not discoveries guaranteed by the data. section 3.2.2
Topic and pageviews
To study how Topic affects Pageviews, connect Topic to Platform and Pageviews. Seasonality and Popularity confound the relationship, while Platform mediates part of Topic’s effect. The graph makes these roles explicit before choosing an analysis. section 3.2.2
A graph is not automatically recoverable from observational data. Correlation does not reveal arrow direction: both X → Y and Y → X can generate the same joint distribution without additional assumptions. Directed acyclic graphs also cannot represent simultaneous feedback directly; time-series data can sometimes unfold such relationships over time. section 3.2.2

