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Deployed Model · E8-P9

PERFORMANCE

Logistic Regression on 500,000 word + character TF-IDF features + 25 engineered numerical features + modular Rule Engine · trained on 195,776 deduplicated message clusters · decision threshold 0.59

About these numbers

Headline metrics below are for the deployed E8-P9 pipeline (classifier + Rule Engine) on a locked one-shot benchmark of 25,306 messages held out from all model selection, hyperparameter search, calibration, and threshold tuning. The pure classifier baseline (no Rule Engine) scores F1 = 0.941 on the same benchmark — that number is preserved as a reference in the API's /stats endpoint. Every scoring event on the benchmark is recorded in the research repository.

Accuracy

Out of all messages, how many did we classify correctly?

Precision

Of messages we called SCAM, what fraction really were scams?

Recall

Of all real scams in the dataset, what fraction did we catch?

F1 Score

Balanced average of Precision and Recall — the key overall quality score.

96.87

%

Accuracy

91.31

%

F1 Score

99.07

%

ROC-AUC

91.02

%

Precision

91.60

%

Recall

12.00

Scam Types

Signal Analysis · Live Variance

MODEL SIGNALS

Confidence separation, precision–recall tradeoff, and external benchmark headline

Confidence Separation

Score deviation from decision threshold (t = 0.59)

91.0%
Precision
91.6%
Recall
zero baselineConfidence

Precision–Recall Balance

P − R gap across threshold sweep (zero = balanced)

t = 0.1
High recall
t = 0.9
High prec.
zero baselinePrecision–Recall

External Benchmark

Locked one-shot set · n = 25,306 · never seen at training

0.964
PR-AUC
0.913
F1
zero baselineExternal

Prediction Quality · Threshold Analysis

DIAGNOSTIC CURVES

How model behaviour shifts across operating points and confidence levels

Precision vs Recall

Threshold sweep on external benchmark (production point at t = 0.59)

Precision Recall▲ optimal @ 0.59

Confidence Distribution

Score buckets on external benchmark — scam vs legit share

Scam % Legit %

Recall by Scam Category

Real-world detection rate per scam type (external benchmark)

Dashed line = overall recall (0.916) · Per-category recall on 25,306 messages

Classifier Quality · External Benchmark

ROC & CONFUSION

How well the model separates scam from legitimate messages on the 25,306-message held-out set

ROC Curve

ROC-AUC = 0.991 · Near-perfect separation

Logistic Regression + Rule Engine · well-calibrated (ECE 0.013)ROC-AUC = 0.991

Confusion Matrix

Predictions on the 25,306-message external benchmark

4,154
True Positive
Correct scam catches
381
False Negative
Missed scams
410
False Positive
Legit flagged as scam
20,361
True Negative
Correct legit calls

External benchmark · 25,306 messages · threshold = 0.59 · accuracy = 96.87%

Real-World Performance

BY SCAM CATEGORY

Recall on scam classes · false-positive rate on legitimate classes · external benchmark

Scam-Class Recall

% of scams in each category correctly flagged

Recruitment scams remain the weakest single class — real recruiter language and scam recruiter language look similar at first message.

Legit-Class False-Positive Rate

% of legitimate messages wrongly flagged (lower is better)

Formal emails have the highest false-positive rate — they use scam-adjacent language (deadlines, verification, dollar amounts).

Training Data

DATASET COMPOSITION

253,264 messages across 12 public corpora — every source has a documented URL and license

Message counts per source

Scam vs legitimate breakdown before deduplication

After SHA-1 exact-dedup + MinHash near-dedup: 195,776 unique message clusters used for training. Cluster-aware train / val / test split prevents near-duplicates from crossing the boundary.

Research Journey · E2 → E8-P9

MODEL DEVELOPMENT

External benchmark PR-AUC and F1 across every stage that led to the deployed E8-P9 pipeline

E-Series Progression

Each stage builds on the previous under strict cluster-grouped evaluation

E2 · Feature ablation
F1–F6 tested. F3 (word + char TF-IDF) wins on external PR-AUC.
E3 · Model bake-off
Logistic Regression, LinearSVC, Random Forest tested on F3. LogReg wins.
E4 · Hyperparameter search
20-trial Optuna HPO. Best PR-AUC improvement +0.005.
E5 · Threshold selection
No calibration needed (uncalibrated ECE 0.011 vs Platt 0.076). Threshold set at 0.59 (F1-max on validation).
E7-P1 · Feature fusion
25 engineered numerical features (tone · URL · phrase · text stats) fused with TF-IDF. Each family reduces FP rate.
E8-P9 · Deployed
Corpus expanded with modern synthetic scams + rule engine (Critical / Strong / Legit). Confirmed via final bake-off vs LinearSVC + SGD.