topics in business intelligence k-nn & naive bayes – group 1 isabel van der lijke nathan bok...

TOPICS IN BUSINESS INTELLIGENCEK-NN & Naive Bayes – GROUP 1

Isabel van der LijkeNathan BokGökhan Korkmaz

INTRODUCTION K-NN

k-NN Classifier (Categorical Outcome) Determining Neighbors Classification Rule Example: Riding Mowers Choosing k Setting the Cutoff Value Advantages and shortcomings of k-NN algorithms

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INTRODUCTION NAIVE BAYES

Basic Classification Procedure Cutoff Probability Method Conditional Probability Naive Bayes Advantages and shortcomings of the naive Bayes

classifier

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SIMPLE CASE APPLICATION

Depression

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SIMPLE CASE APPLICATION

Fruits

Example: P(Banana) = 500 / 1000 = 0,5

1-0,5 = 0,5 (Not banana)

New fruit compute all the chances

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Sweet Not sweet

Total

Banana 350 150 500Orange 150 150 300Other fruit 150 50 200Total 650 350 1000

REAL-LIFE APPLICATION NAIVE BAYES

Medical Data Classification with Naive Bayes Approach Introduction Requirements for systems dealing with medical data An empirical comparison Tables Conclusion

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TABLE 2:COMPARATIVE ANALYSIS BASED ON PREDICTIVE ACCURACY

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TABLE 3:COMPARATIVE ANALYSIS BASED ON AREA UNDER ROC CURVE (AUC)

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REAL-LIFE APPLICATION K-NN

Used to help health care professionals in diagnosing heart disease.

Useful for pattern recognition and classification. Euclidean distance:

Often normalized data due to different variable formats.

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CASE STUDY

“Our customer is a Dutch charity organization that wants to be able to classify it's supporters to donators and non-donators. The non-donators are sent a single marketing mail a year, whereas the donators receive multiple ones (up to 4).”

Who are the donators? Who are the non-donators?

Application of K-NN & Naive Bayes to training and test dataset. 4000 customers. SPSS, Excel, XLMiner

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CLEAN-UP

No missing values 1-dimensional outliers removed through sorting

(regarding annual & average donation) 2-dimensional outliers removed through scatterplot

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Variables Kept

Average donation

Frequency of Response

Median Time of Response

Time as client

Variables removedAnnual donationLast donationTime since last response.

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Normalization of scores into z-scores. Nominal categorization of data Classification through percentiles of z-score & by

manually processing values within the variables.

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ANALYSIS OF CASE STUDY – K-NN

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Validation Data Scoring - Summary Report (for k = 13)

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Error ReportClass # Cases # Errors % Error

0 1083 180 16,62049861

1 536 260 48,50746269

Overall 1619 440 27,17726992

Classification Confusion Matrix Predicted Class

Actual Class 0 1

0 903 180

1 260 276

CHOOSING MODEL FOR K-NN

Accuracy: Proportion of correctly classified instances. Error rate: (1 – Accuracy) Sensitivity: Sensitivity is the proportion of actual

positives which are correctly identified as positives by the classifier.

Specificity: Like sensitivity, but for the negatives.

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M1 M2Selecting everyone in validation data

€711.20 €662.80

Selecting while correcting for sensitivity and specificity

€583.60 €530.80

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APPLICATION OF MODEL ON TEST DATA

Classification Confusion Matrix

Predicted Class

Actual Class 0 1

0 2300 344

1 654 750

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0 2644 344 13,01059

1 1404 654 46,5812

Overall 4048 998 24,65415

ANALYSIS OF THE CASE STUDY – NAIVE BAYES

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Predicted Class

Actual Class 0 1

0 856 229

1 225 309


0 1085 229 21,10599

1 534 225 42,13483

Overall 1619 454 28,042

M1 = Cfrqres & Cavgdon M2 = Cfrqresp, Cavgdon

& Cmedtor

Classes -->

InputVariables

0 1

Value Prob Value Prob

CFRQRES

1 0,71977 1 0,2974832 0,171465 2 0,2551493 0,06398 3 0,192224 0,044786 4 0,255149

CAVGDON

1 0,632758 1 0,2974832 0,272553 2 0,4713963 0,076136 3 0,164764 0,018554 4 0,066362

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Model 1 Model 2

Selecting everyone €1072 €1006

Selecting by class €2460,82 €2378.01

APPLICATION OF MODEL ON TEST DATA

Classes -->

InputVariables

0 1

Value Prob Value Prob

CFRQRES

1 0,714502 1 0,3061082 0,173338 2 0,2542613 0,066465 3 0,186084 0,045695 4 0,253551

CAVGDON

1 0,630287 1 0,31252 0,280589 2 0,4616483 0,068353 3 0,1683244 0,02077 4 0,057528

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Predicted

Class

Actual Class 0 1

0 2096 548

1 570 834


0 2644 548 20,72617

1 1404 570 40,59829

Overall 4048 1118 27,61858

LOOKING AT BOTH MODELS

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QUESTIONS?

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