Table 1 Summary table of performance measures of the investigated ML algorithms developed on human expert-annotated features (HEAF).

From: Comparative analysis of machine learning algorithms for computer-assisted reporting based on fully automated cross-lingual RadLex mappings

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Method

ML Classifier

HEAF feature space

Rank

Software

Optimized metric

Tested hyperparameter space

Selected number of features or hyperparameter settings on outer fold 1.0–5.0

Accuracy# [min–max; %]

ME

AUC

BS

LL

Human Expert-Annotated Features (HEAF)

CART

CT

p = 28 (all)

 

rpart [R]

ACC

rpart.control = default; cp = 0.01 no optimization (no pruning)

28

73.3 [66.7–79.2]

0.27

0.63

0.37

0.87

vRF

RF

p = 28 (all)

4

randomForest [R]

ME

ntree = 500, mtry = 5, pvarsel = 28

28

81.5 [73.8–92.7]

0.18

0.82

0.27

0.44

vRF

RF

p = 28 (all)

 

randomForest[R]

ME

ntree = 500, mtry = 5, pvarsel = 9

9

71.0 [59.5–82.9]

0.29

0.69

0.37

0.56

vRF

RF

p = 28 (all)

 

randomForest[R]

ME

ntree = 500, mtry = 5, pvarsel = 5

5

75.2 [68.3–83.3]

0.25

0.69

0.36

0.54

tRFBS

RF

p = 28 (all)

2

randomForest[R]

BS

ntree = [100, 200, 300, … , 900, 1000]

28, 14, 14, 14, 14

83.1 [76.2–90.2]

0.17

0.81

0.27

0.44

tRFME

RF

p = 28 (all)

 

randomForest[R]

ME

mtry = [3, 4, 5, 6, 7]

28, 28, 14, 5, 14

79.6 [68.3–90.2]

0.20

0.79

0.29

0.46

tRFLL

RF

p = 28 (all)

2

randomForest[R]

LL

pvarsel = [3, 5, 10, 14, 20, 25, 28]

25, 14, 14, 14, 14

83.1 [76.2–90.2]

0.17

0.81

0.27

0.44

ELNET

ELNET

p = 28 (all)

3

glmnet[R]

ME

α = [0, 0.1, 0.2, … , 0.8, 0.9, 1] λ = tenfold CV with default hot-start

α = [0.1, 0.8, 0, 1, 0.1] λ = [0.195, 0.0688, 0.208, 0.0301, 0.1632]

82.0 [78.6–85.4]

0.18

0.79

0.27

0.43

SVM-LK

SVM

p = 28 (all)

1

e1071[R]

ME

C = [0.001, 0.01, 0.1, 1, 10, 100, 1000]

C = [1, 1, 100, 10, 10]

87.4 [82.9–90.2]

0.13

0.79

0.22

0.37

XGBoost

BT

p = 28 (all)

5

xgboost[R]

ME

nrouds/ntree = 100,

nrouds = 100

80.6 [75.0–85.7]

0.19

0.70

0.30

0.48

max_depth = [3, 5, 6, 8]

max_depth = [5, 3, 5, 8, 3]

eta = [0.1, 0.3]

eta = [0.1, 0.1, 0.1, 0.3, 0.1]

gamma = [0, 0.5, 1.0]

gamma = [0, 0.5, 1, 0.5, 1]

colsample_bytree = [0.1, 0.25, 0.5, 0.693 (ln2) ~ RF, 1]

colsample_bytree = [1, 1, 0.5, 1, 0.5]

  1. Accuracy#: the averaged fivefold CV accuracy is calculated, ACC: accuracy, AUC: multiclass area under the ROC after Hand and Till (that can only be calculated if probabilities are scaled to 1), BS: Brier score, ME: misclassification error, LL: multiclass log loss, vRF and tRF: vanilla- and tuned random forests, ELNET: elastic net penalized multinomial logistic regression, SVM: support vector machines, LK: linear kernel SVM; XGBoost: extreme gradient boosting using trees as base learners, BT: boosted trees, CART: classification and regression trees; CT: classification tree; cp: complexity parameter used for CART node splitting (for this no optimization (pruning) was performed); ln(2) ~ RF: column sampling (i.e. bootstrap) representing the settings equivalent to running RF in the xgboost library, [R]: R statistical software environment.