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Chai Biscuit
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Decision Tree
What is Decision Tree?
A decision tree is a tree based modeling technique used to determine a
class/event given a certain input.
3 Important
Parts of Decision Tree
1. Root Node -> has no incoming edge but
outgoing edge(s)
2. Leaf or Terminal Node
-> has exactly
one incoming edge and no outgoing edge.
3. Intermediary Node ->
has exactly one incoming
edge and two or more outgoing
Structure of Decision Tree
pending: Insert image
Decision
Tree Algorithms
·
Hunt’s Algorithm
·
Ross Quinlan
§ i.ID3
§ ii.C4.5
§ iii.C5.0
·
Breiman et al.
o CART (Classification
and Regression Trees)
·
Gordan Kass
§ i.CHAID (chi-square
automatic interaction detector)
Hunt’s
Algorithm
Hunt’s algorithm is recursive.
Let
Si =set of
training records, that reach a node i
Steps
1. If Sicontains
records that belong the same class yi, then ‘i’ is a leaf node labeled as yi
2. If Sicontains
records that belong to more than one class, use an attribute test to split the
data into smaller subsets. Recursively apply the procedure to each subset.
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