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anytime algorithms for learning anytime classifiers saher ... - Technion

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<strong>Technion</strong> - Computer Science Department - Ph.D. Thesis PHD-2008-12 - 2008<br />

Table 3.4: The average differences in tree-size between the different <strong>algorithms</strong> and<br />

their t-test significance, with α = 0.05 ( √ indicates a significant advantage and × a<br />

significant disadvantage). The t-test is not applicable <strong>for</strong> the Monk datasets because<br />

only 1 train-test partition was used.<br />

LSID3 vs. ID3 LSID3 vs. C4.5 LSID3-P vs. C4.5<br />

Dataset Diff Sig? Diff Sig? Diff Sig?<br />

Autos Make<br />

Autos Sym.<br />

Balance<br />

Br. Cancer<br />

Connect-4<br />

Corral<br />

Glass<br />

Iris<br />

-17.1 ±4.8<br />

-19.9 ±2.2<br />

-6.2 ±5.0<br />

-29.3 ±5.6<br />

-3976 ±265<br />

-2.5 ±2.2<br />

-4.4 ±3.0<br />

-0.9 ±0.7<br />

√<br />

√<br />

√<br />

√<br />

√<br />

√<br />

√<br />

√<br />

9.9 ±2.4<br />

6.6 ±4.1<br />

312.8 ±9.8<br />

94.2 ±5.4<br />

11201 ±183<br />

1.4 ±1.3<br />

10.3 ±3.1<br />

2.9 ±1.0<br />

×<br />

×<br />

×<br />

×<br />

×<br />

×<br />

×<br />

×<br />

10.4 ±2.2<br />

6.3 ±4.3<br />

5.2 ±7.7<br />

1.7 ±8.5<br />

3284 ±186<br />

1.0 ±1.3<br />

11.6 ±3.7<br />

1.9 ±1.6<br />

×<br />

×<br />

×<br />

∼<br />

×<br />

×<br />

×<br />

×<br />

Monks-1 -35.0 ±0.0 - 16.0 ±0.0 - 10.0 ±0.0 -<br />

Monks-2 -16.6 ±3.4 - 72.4 ±3.4 - -1.7 ±5.0 -<br />

Monks-3<br />

Mushroom<br />

Solar-Flare<br />

Tic-tac-toe<br />

Voting<br />

Wine<br />

Zoo<br />

Numeric XOR-3D<br />

Numeric XOR-4d<br />

Multiplexer-20<br />

Multiplex-XOR<br />

XOR-5<br />

XOR-5 Noise<br />

XOR-10<br />

-4.2 ±1.6<br />

-7.8 ±0.9<br />

-5.6 ±2.5<br />

-37.3 ±15.1<br />

-0.6 ±2.1<br />

-1.7 ±1.2<br />

-3.9 ±0.9<br />

-33.8 ±5.1<br />

-77.9 ±6.0<br />

-96.1 ±21.6<br />

-40.1 ±7.3<br />

-60.3 ±7.8<br />

-35.4 ±8.3<br />

-1897 ±587<br />

√<br />

-<br />

√<br />

√<br />

√<br />

√<br />

√<br />

√<br />

√<br />

√<br />

√<br />

√<br />

√<br />

√<br />

17.8 ±1.6<br />

-2.8 ±0.9<br />

61.2 ±3.1<br />

68.3 ±9.3<br />

10.2 ±2.5<br />

0.9 ±1.0<br />

1.6 ±1.2<br />

8.2 ±1.0<br />

24.1 ±4.8<br />

-19.4 ±20.4<br />

17.9 ±8.1<br />

10.1 ±5.3<br />

35.0 ±8.9<br />

637 ±577<br />

√<br />

-<br />

×<br />

×<br />

×<br />

×<br />

×<br />

×<br />

√<br />

×<br />

×<br />

×<br />

×<br />

×<br />

0.9 ±1.4<br />

-2.9 ±0.9<br />

-0.8 ±1.4<br />

29.1 ±10.9<br />

0.7 ±2.4<br />

2.1 ±1.6<br />

1.5 ±1.2<br />

10.7 ±1.7<br />

28.1 ±6.3<br />

-24.9 ±17.4<br />

5.7 ±7.0<br />

10.1 ±5.3<br />

17.2 ±8.1<br />

273 ±524<br />

√<br />

-<br />

√<br />

×<br />

×<br />

×<br />

×<br />

×<br />

√<br />

×<br />

×<br />

×<br />

×<br />

×<br />

that of ID3 on some datasets. ID3-k achieved similar results to LSID3 <strong>for</strong> some<br />

datasets, but per<strong>for</strong>med much worse <strong>for</strong> others, such as Tic-tac-toe and XOR-<br />

10. For most datasets, the decrease in the size of the trees induced by LSID3 is<br />

accompanied by an increase in predictive power. This phenomenon is consistent<br />

with Occam’s Razor.<br />

Pruned Trees<br />

Pruning techniques help to avoid overfitting. We view pruning as orthogonal to<br />

our lookahead approach. Thus, to allow handling noisy datasets, we tested the<br />

per<strong>for</strong>mance of LSID3-p, which post-prunes the LSID3 trees using error-based<br />

pruning.<br />

Figure 3.22 compares the per<strong>for</strong>mance of LSID3-p to that of C4.5. Applying<br />

50

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