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Presentation Title Department of Computer Science A More Principled Approach to Machine Learning Michael R. Smith Brigham Young University Department of Computer Science 2 February 2015
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Presentation Title Department of Computer Science Machine Learning Learn from past experience Change their behavior without explicitly being programed Optimization techniques Maximize accuracy Minimize error Mine data 2
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Presentation Title Department of Computer Science Machine Learning Example I, Robot 3
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Presentation Title Department of Computer Science Machine Learning 4
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Presentation Title Department of Computer Science 5 Machine Learning WeightHeightBlood Press Temp 20578good98.2 15765bad100.7 18571mod99.5 Learning Algorithm Training Data WeightHeightBlood Press Temp 17267bad100.1 Has Disease yes no Has Disease ?
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Presentation Title Department of Computer Science 6 Machine Learning
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Presentation Title Department of Computer Science 7 Machine Learning WeightHeightBlood Press TempHas Disease 20578good98.2 Yes 15765bad100.7 Yes 18571mod99.5 No WeightHeightBlood Press Temp 17267bad100.1 Has Disease ? Data Set# Features# ClassesEntropy…# NodesLearning Rate…Accuracy Disease420.24…30.1…83.4 Iris430.76…70.2…97.4 Meta-data
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Presentation Title Department of Computer Science 8 Meta-Learning Data Set# Features# ClassesEntropy…# NodesLearning Rate…Accuracy Disease420.24…30.1…83.4 Iris430.76…70.2…97.4 Data Set# Features# ClassesEntropy… Ecology1730.5… Meta-features
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Presentation Title Department of Computer Science Meta-Learning 9
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Presentation Title Department of Computer Science Meta-Learning 10
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Presentation Title Department of Computer Science Previous Work 11 Random Search
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Presentation Title Department of Computer Science Instance Hardness Learning algorithms are generally evaluated at the data set level Are some instances intrinsically hard to classify? Why are some instances misclassified? Are there instances which are misclassified that should not be? Are some instances misclassified by all learning algorithms? If so, why? 12
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Presentation Title Department of Computer Science Data Set 13
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Presentation Title Department of Computer Science Overfit 14
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Presentation Title Department of Computer Science 15 Linear Classifier
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Presentation Title Department of Computer Science 16 Detrimental Instances
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Presentation Title Department of Computer Science Instance Hardness Better intuition of learning algorithms and why instances are misclassified Can learning algorithms be improved? Where? Informed analysis of learning algorithm performance Is the classification reasonable? Where can the quality of the data be improved Empirical analysis of the classification of 57 data sets by 9 learning algorithms 10-fold cross-validation 178,109 instances 5,310 models were created 17
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Presentation Title Department of Computer Science Instance Hardness 18
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Presentation Title Department of Computer Science Instance Hardness 19 9 learning algorithms C4.5 MLP RIPPER NNge Ridor Unsupervised Meta-learning Cluster learning algorithms based on diversity Intuition for all of the algorithms in the cluster 5NN Random Forest LWL Naïve Bayes
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Presentation Title Department of Computer Science Existence of Instance Hardness 20 53% correctly classified by all algorithms 5% misclassified by all algorithms Learning algorithms disagree on 42% of the instances 15% misclassified by the majority of algorithms
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Presentation Title Department of Computer Science 21 Modeling Detrimental Instances True class label is generally ignored Regularization Validation sets Pruning
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Presentation Title Department of Computer Science 22 Modeling Detrimental Instances
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Presentation Title Department of Computer Science Instance Quality Learning 23
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Presentation Title Department of Computer Science 24 Inequality Learning
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Presentation Title Department of Computer Science 25 0.00019 0.678 0.054 Inequality Learning
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Presentation Title Department of Computer Science Results: Original MLPC4.55-NNLWLNBNngeRandFRidorRip Orig80.780.17969.475.779.481.676.677.8 QW-L83.880.18070.477.279.483.378.679.7 p-val< 0.0010.0450.015 0.014< 0.0010.788< 0.0010.036< 0.001 g,e,l47,0,532,0,2035,1,1628,10,1435,1,1620,1,2733,1,1831,1,1938,0,14 QW-B84.682.380.368.275.279.483.578.678.8 p-val< 0.001 0.0160.5900.8580.877< 0.0010.013< 0.001 g,e,l49,0,337,1,1432,0,2022,12,1819,1,3221,1,2632,2,1834,1,1637,3,12 Filter82.981.882.370.077.382.483.279.579.7 p-val< 0.001 0.032< 0.001 g,e,l39,0,1338,3,1138,4,1026,12,1436,1,1540,0,1233,1,1835,3,1440,2,10 26
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Presentation Title Department of Computer Science Results: Original 27 MLPC4.55-NNLWLNBNngeRandFRidorRip Orig80.780.17969.475.779.481.676.677.8 QW-L83.880.18070.477.279.483.378.679.7 p-val< 0.0010.0450.015 0.014< 0.0010.788< 0.0010.036< 0.001 g,e,l47,0,532,0,2035,1,1628,10,1435,1,1620,1,2733,1,1831,1,1938,0,14 QW-B84.682.380.368.275.279.483.578.678.8 p-val< 0.001 0.0160.5900.8580.877< 0.0010.013< 0.001 g,e,l49,0,337,1,1432,0,2022,12,1819,1,3221,1,2632,2,1834,1,1637,3,12 Filter82.981.882.370.077.382.483.279.579.7 p-val< 0.001 0.032< 0.001 g,e,l39,0,1338,3,1138,4,1026,12,1436,1,1540,0,1233,1,1835,3,1440,2,10
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Presentation Title Department of Computer Science Inequality Learning 28 Increases the accuracy for all of the investigated learning algorithms Advantage to using a continuous value rather than binary Most effective in global learning algorithms such as backpropagation Could be a side effect of how we integrated instance quality into the learning algorithm. (Future Work) Focusing on the data, how does it compare with hyper-parameter optimization (HPO)?
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Presentation Title Department of Computer Science Comparison of HPO and Filtering 29
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Presentation Title Department of Computer Science K-Fold Cross-Validation Create K partitions of the data set For each partition, use as testing and remaining K-1 partitions for training 30
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Presentation Title Department of Computer Science K-Fold Cross-Validation Use a validation set to determine which set of hyper- parameters to use 31 Validation examples
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Presentation Title Department of Computer Science Experimental Methodology 32 Hyper-parameter optimization Bayesian Optimization (more than 512 hyper-parameter settings explored for most learning algorithms) Standard uses the accuracy on a validation set Optimistic uses the 10-fold cross-validation accuracy Filtering Ensemble Filter (L-Filter) Removes instances that are misclassified by the majority of a set of learning algorithms Adaptive Filter (A-Filter) Greedy search among candidate learning algorithms
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Presentation Title Department of Computer Science Results-Standard Approach VS OrigL-FilterHPO MLP44,1,747,0,5 C4.545,1,639,0,13 kNN44,2,641,2,9 NB42,0,1042,1,9 RF38,3,1137,2,13 RIP50,0,247,1,4
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Presentation Title Department of Computer Science Results-Optimistic Approach 34 Not one filtering approach is best for all data sets and learning algorithms VS HPOL-FilterA-Filter MLP27,3,2245,0,7 C4.533,4,1548,2,2 kNN30,2,2051,0,1 NB22,2,2834,0,18 RF27,1,2446,0,6 RIP34,1,1748,0,4
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Presentation Title Department of Computer Science Why does filtering have such a significant effect? Recall: Maximize the probability of the hypothesis given the data At the instance-level: 35
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Presentation Title Department of Computer Science 36 Example Data Set
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Presentation Title Department of Computer Science A Need for Better Understanding Filter has a much higher potential than HPO No principled examination 37
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Presentation Title Department of Computer Science The Need for a Repository 38
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Presentation Title Department of Computer Science The Need for a Repository 39
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Presentation Title Department of Computer Science The Need for a Repository 40
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Presentation Title Department of Computer Science Benefits of a Repository Better science Reproducible/saved results Save time Build reputation Easier to compare with other work Gives a snapshot of current state Overall Specific data set Meta-learning Provide data set 41
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Presentation Title Department of Computer Science Machine Learning Results Repository 42
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Presentation Title Department of Computer Science Machine Learning Results Repository 43 Data Set-Level Learning Algorithm -Level Instance-Level
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Presentation Title Department of Computer Science Future Directions and Projects MLRR Data quality Linking with papers Creating user profiles Anonymous postings for supplemental material Meta-learning Combine learning with optimization techniques Meta-features Deep learning Collaborative filtering Automate machine learning 44
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Presentation Title Department of Computer Science Future Directions and Projects Incorporate information into the learning process Use cases of machine learning How is machine learning actually used? How can it be made easier to use? Collaboration/application to other fields Bioinformatics Social media Sports statistics 45
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Presentation Title Department of Computer Science Thank you
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