Unknown Attribute Values

What if some examples missing values of $A$?

Use training example anyway, sort through tree If node $n$ tests $A$, assign most common value of $A$ among other examples sorted to node $n$

assign most common value of $A$ among other examples with same target value

assign probability $p_{i}$ to each possible value $v_{i}$ of $A$ assign fraction $p_{i}$ of example to each descendant in tree

Classify new examples in same fashion