Non-Euclidean Models for Fraud Detection

Supplementary Materials

Prediction Probability Distributions

Comparison of predicted fraud probabilities for actual fraud cases (y=1) across different undersampling ratios. Top row: histograms; bottom row: CDFs. Methods with subscript G indicate graph-enhanced versions using GCN embeddings.

Select Model Type:

Undersampling Experiments

We evaluated the robustness of our proposed method across various undersampling ratios while keeping the test set unchanged. Methods with subscript G indicate graph-enhanced versions using GCN embeddings. Highlighted rows show graph-enhanced models.

Table 1: Performance Metrics (Fraud Ratio: 5%)

MethodAccuracyPrecisionRecallF1-scoreAUC
NeuralNet0.99520.55310.86790.67560.9954
NeuralNetG0.99680.65280.94890.77350.9993
RandomForest0.99540.56390.84060.67500.9903
RandomForestG0.99710.67690.92840.78300.9989
ExtraTrees0.99590.60540.83560.70210.9907
ExtraTreesG0.99470.51930.91670.66310.9979
LightGBM0.99460.51880.82070.63570.9933
LightGBMG0.99720.68400.94340.79300.9992
CatBoost0.99570.59660.78850.67930.9772
CatBoostG0.99660.64640.90950.75570.9978
XGBoost0.99510.54770.81680.65570.9899
XGBoostG0.99420.49750.93060.64840.9885
KNeighbors0.98410.08730.18770.11920.7354
KNeighborsG0.98680.11260.18990.14140.7426

Table 2: Performance Metrics (Fraud Ratio: 10%)

MethodAccuracyPrecisionRecallF1-scoreAUC
NeuralNet0.99020.36250.93280.52210.9949
NeuralNetG0.99520.54550.97830.70050.9994
RandomForest0.99300.44530.87450.59010.9931
RandomForestG0.99560.57070.96170.71630.9992
ExtraTrees0.99450.50970.86290.64080.9917
ExtraTreesG0.99240.42620.95890.59010.9988
LightGBM0.99340.46090.90950.61180.9959
LightGBMG0.99600.59140.97720.73690.9994
CatBoost0.99380.47760.86840.61620.9940
CatBoostG0.99590.58820.97060.73250.9991
XGBoost0.99400.48390.83180.61180.9731
XGBoostG0.99490.52980.96220.68340.9978
KNeighbors0.96030.04700.30820.08160.7838
KNeighborsG0.96130.04850.30870.08380.7855

Table 3: Performance Metrics (Fraud Ratio: 20%)

MethodAccuracyPrecisionRecallF1-scoreAUC
NeuralNet0.98110.22350.92890.36030.9924
NeuralNetG0.99160.40550.98720.57480.9991
RandomForest0.98610.27820.89620.42460.9933
RandomForestG0.99100.38690.97780.55450.9989
ExtraTrees0.99100.37800.88730.53020.9918
ExtraTreesG0.98710.30520.97830.46530.9986
LightGBM0.98690.29500.93170.44810.9954
LightGBMG0.99350.46900.99060.63660.9995
CatBoost0.99010.36200.95280.52470.9982
CatBoostG0.99430.50270.98220.66500.9992
XGBoost0.98650.28510.90620.43380.9950
XGBoostG0.99470.52170.98220.68140.9994
KNeighbors0.90160.02950.50690.05570.8111
KNeighborsG0.90170.02950.50690.05580.8114

Table 4: Performance Metrics (Fraud Ratio: 30%)

MethodAccuracyPrecisionRecallF1-scoreAUC
NeuralNet0.97070.15760.94780.27030.9926
NeuralNetG0.98530.27800.98390.43350.9980
RandomForest0.97800.19760.92670.32580.9935
RandomForestG0.98530.27820.98330.43370.9987
ExtraTrees0.98600.27920.90890.42720.9925
ExtraTreesG0.97730.19930.98390.33140.9981
LightGBM0.97480.17830.94280.29990.9950
LightGBMG0.98920.34550.99110.51230.9991
CatBoost0.98490.27190.97390.42510.9983
CatBoostG0.99170.40860.98830.57820.9993
XGBoost0.97680.19000.93340.31580.9947
XGBoostG0.99240.42760.98950.59720.9994
KNeighbors0.83800.02210.63190.04270.8115
KNeighborsG0.84040.02270.63850.04380.8163

Table 5: Performance Metrics (Fraud Ratio: 40%)

MethodAccuracyPrecisionRecallF1-scoreAUC
NeuralNet0.94670.09240.94170.16820.9883
NeuralNetG0.98060.22660.99280.36900.9975
RandomForest0.96920.15060.94340.25980.9937
RandomForestG0.97950.21690.98830.35570.9986
ExtraTrees0.97970.21010.92060.34220.9926
ExtraTreesG0.97150.16580.98780.28390.9979
LightGBM0.97110.16000.95390.27410.9942
LightGBMG0.98700.30450.99560.46640.9991
CatBoost0.97780.20230.97720.33510.9977
CatBoostG0.98900.34100.99110.50740.9992
XGBoost0.96770.14590.95670.25320.9946
XGBoostG0.98880.33720.99060.50320.9992
KNeighbors0.77030.01760.71520.03440.8047
KNeighborsG0.77090.01770.71740.03460.8069

Table 6: Performance Metrics (Fraud Ratio: 50%)

MethodAccuracyPrecisionRecallF1-scoreAUC
NeuralNet0.93600.07880.95280.14560.9890
NeuralNetG0.97690.19760.99330.32970.9969
RandomForest0.95870.11790.95720.20990.9931
RandomForestG0.97350.17660.98950.29970.9982
ExtraTrees0.96780.14490.94450.25130.9928
ExtraTreesG0.96490.13900.98950.24380.9977
LightGBM0.95810.11670.96220.20810.9936
LightGBMG0.98040.22550.99720.36780.9987
CatBoost0.96910.15440.98280.26680.9972
CatBoostG0.98750.31440.99560.47790.9994
XGBoost0.95750.11610.97060.20750.9943
XGBoostG0.98400.26180.98950.41410.9989
KNeighbors0.68950.01430.78460.02810.7971
KNeighborsG0.68990.01440.78570.02820.7985