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Decision Trees from large Databases: SLIQ

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Compare: Information Gain vs. Gini Index<br />

• Which split is better?<br />

[29 +, 35 -]<br />

yes<br />

x 1<br />

x 2<br />

no<br />

• H L, y = − 29<br />

64 log 2 29<br />

64 + 35<br />

64 log 2 35<br />

64<br />

= 0.99<br />

[29 +, 35 -]<br />

[21+, 5 -] [8+, 30 -] [18+, 33 -] [11+, 2 -]<br />

• IG L, x 1 = 0.99 − 26<br />

64 H L x 1 =yes, y + 38<br />

64 H L x 1 =no, y ≈ 0.26<br />

• IG L, x 2 = 0.99 − 51<br />

64 H L x 2 =yes, y + 13<br />

64 H L x 2 =no, y ≈ 0.11<br />

1 − 8 38<br />

• Gini x1 L = 26<br />

64 Gini L x 1 =yes + 38<br />

64 Gini L x 1 =no ≈ 0.32<br />

• Gini x2 L = 51<br />

64 Gini L x 2 =yes + 13<br />

64 Gini L x 2 =no ≈ 0.42<br />

43<br />

yes<br />

2<br />

+<br />

30<br />

38<br />

2<br />

no<br />

≈ 0.33<br />

Sawade/Landwehr/Prasse/Scheffer, Maschinelles Lernen

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