add wikipedia link to DAG

Author: drbenvincent

examples/generalized_linear_models/GLM-simpsons-paradox.ipynb

@@ -849,7 +849,7 @@
    "source": [
     "## Model 2: Unpooled regression\n",
     "\n",
-    "We will use the same data in this analysis, but this time we will use our knowledge that data come from groups. From a causal perspective we are exploring the notion that both $x$ and $y$ are influenced by group membership. This can be shown in the causal DAG below.\n"
+    "We will use the same data in this analysis, but this time we will use our knowledge that data come from groups. From a causal perspective we are exploring the notion that both $x$ and $y$ are influenced by group membership. This can be shown in the causal directed acyclic graph ([DAG](https://en.wikipedia.org/wiki/Directed_acyclic_graph)) below.\n"
    ]
   },
   {

examples/generalized_linear_models/GLM-simpsons-paradox.myst.md

@@ -258,7 +258,7 @@ ax.set(title="Model 1 strongly suggests a positive slope", xlabel=r"$\beta_1$");
 
 ## Model 2: Unpooled regression
 
-We will use the same data in this analysis, but this time we will use our knowledge that data come from groups. From a causal perspective we are exploring the notion that both $x$ and $y$ are influenced by group membership. This can be shown in the causal DAG below.
+We will use the same data in this analysis, but this time we will use our knowledge that data come from groups. From a causal perspective we are exploring the notion that both $x$ and $y$ are influenced by group membership. This can be shown in the causal directed acyclic graph ([DAG](https://en.wikipedia.org/wiki/Directed_acyclic_graph)) below.
 
 ```{code-cell} ipython3
 :tags: [hide-input]