fraud-detection-system-with-explainable-ai

🔍 Real-Time Fraud Detection System with Explainable AI & Live Dashboard

Week 3 & 4 Project | AI & Data Analyst Internship

An end-to-end fraud detection pipeline combining state-of-the-art machine learning, severe class imbalance handling, Explainable AI (SHAP), and a live interactive Streamlit dashboard — built to simulate real analyst work at a fintech or banking firm.

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📌 Problem Statement

Financial fraud costs the global economy over $5 trillion annually. Credit card fraud, identity theft, and transaction anomalies demand systems that can detect suspicious activity in milliseconds — not after the damage is done. Legacy rule-based systems miss novel attack patterns; simple ML models are black boxes that compliance teams can't trust.

This project builds an end-to-end Fraud Detection System that:

• Handles severe class imbalance using SMOTE
• Trains and compares multiple advanced ML models
• Uses SHAP to explain every prediction in plain English
• Packages results in a live Streamlit dashboard a real fraud analyst could deploy and trust

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📁 Repository Structure

fraud-detection-system-with-explainable-ai/
│
├── Analysis.ipynb          # Main Colab Notebook (Tasks 1–5, 7–8)
├── Dashboard/              # Streamlit multi-page dashboard application
├── Chart/                  # All generated visualization charts
├── Dataset/                # Kaggle dataset link (CSVs not included due to large file size)
├── sample_data.csv         # Sample dataset for dashboard demo
├── Model_Comparison.png    # Side-by-side model performance comparison
├── Shap_Summary.png        # SHAP global feature importance summary plot
├── Summary.pdf             # Final insights & business recommendations report
├── requirements.txt        # All required Python libraries
└── .devcontainer/          # Dev container config for reproducible environment

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✅ Tasks Completed

Task 1 — Data Loading, Merging & Exploratory Analysis

• Loaded both CSVs and merged on TransactionID using Pandas
• Displayed shape, dtypes, and first 10 rows of the merged dataset
• Analysed the isFraud target column — quantified and visualized class imbalance
• Identified missing values column-by-column
• Applied drop vs. impute threshold — dropped columns with >50% missing values
• Plotted TransactionAmt distribution for fraud vs. non-fraud using log scale
• Computed a correlation heatmap of the top 20 numerical features using Seaborn

Task 2 — Preprocessing, Imbalance Handling & Feature Engineering

• Dropped high-missing columns (>50% threshold)
• Imputed remaining values: Median (numerical), Mode (categorical)
• Applied Label Encoding on high-cardinality categorical columns (strategy justified in Markdown)
• Engineered 3 new features:
  • AmtToMeanRatio = TransactionAmt / mean(TransactionAmt)
  • HourOfDay = extracted from TransactionDT
  • DeviceRisk = binary flag based on DeviceType and DeviceInfo
• Applied SMOTE on the training set only to handle class imbalance
• Scaled numerical features using RobustScaler
• Performed stratified 80/20 train-test split
• Reported class ratio before and after SMOTE

Task 3 — Model Training, Comparison & Threshold Optimization

• Trained 3 classification models:
  • Model 1: LightGBM Classifier
  • Model 2: XGBoost Classifier
  • Model 3: Isolation Forest
• Evaluated all models with: Accuracy, Precision, Recall, F1-Score, ROC-AUC, PR-AUC
• Plotted Confusion Matrix for each model
• Plotted ROC Curve and Precision-Recall Curve for all models
• Optimized classification threshold using Threshold vs F1-Score plot (Advanced)
• Tuned best model using Optuna / RandomizedSearchCV (Advanced)
• Documented all improvements in Markdown

Task 4 — Explainable AI with SHAP Values (Advanced)

• Installed and ran the SHAP library
• Generated Global SHAP Summary Plot (top 20 features) → Shap_Summary.png
• Generated SHAP Waterfall Plots for 3 transaction cases:
  • Confirmed fraud transaction
  • Borderline case (~0.50 probability)
  • Legitimate transaction
• Generated SHAP Dependence Plot for key features
• Explained all 3 transactions in plain English for non-technical stakeholders
• Compared SHAP importance vs model feature importance

Task 5 — Risk Segmentation & Fraud Pattern Analysis (Advanced)

• Segmented all transactions using fraud probability into 3 risk tiers:
  • 🔴 Critical Risk → probability ≥ 0.75
  • 🟡 Suspicious → probability between 0.40 and 0.74
  • 🟢 Clear → probability < 0.40
• Counted transactions per tier and computed per-tier averages:
  • Average TransactionAmt, device type distribution, hour-of-day pattern
• Created grouped bar chart comparing all 3 tiers across key features
• Identified top 3 fraud patterns from Critical Risk transactions

Task 6 — Streamlit Fraud Operations Dashboard (Advanced)

Built a multi-page Streamlit application with:

• Page 1 — Overview: Total transactions, fraud count, detection rate, average fraud amount
• Page 2 — Transaction Explorer: Searchable & filterable table with live risk score by TransactionID
• Page 3 — SHAP Explainer: User enters TransactionID → SHAP waterfall plot + plain-English explanation

Additional features:

• Sidebar filters
• Plotly interactive charts
• Deployed on Streamlit Community Cloud

🔗 Live Dashboard: (https://fraud-detection-system-with-explainable-ai-5rtlqu5k7cchtzgsfee.streamlit.app/)

Task 7 — Visualizations (5+ Charts)

• Chart 1: SHAP Global Summary Plot → Shap_Summary.png
• Chart 2: Fraud rate by hour of day
• Chart 3: TransactionAmt distribution (fraud vs. non-fraud, log scale)
• Chart 4: Risk tier donut chart (Critical / Suspicious / Clear)
• Chart 5: Precision-Recall Curve with optimal threshold marked
• Bonus: Interactive Plotly scatter plot — TransactionAmt vs HourOfDay, colored by fraud probability

All charts saved in the Chart/ folder. Model comparison: Model_Comparison.png

Task 8 — Insights & Business Recommendations

A structured analysis written inside the notebook covering:

• Which model performed best and why
• Why PR-AUC matters more than accuracy in fraud detection
• Top 3 fraud signals identified by SHAP
• Common characteristics of Critical Risk transactions
• 2 actionable fraud prevention policies
• Estimated annual money saved
• Model limitations and additional data that could improve performance

Full written summary: Summary.pdf

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📦 Dataset

The dataset used in this project is the IEEE-CIS Fraud Detection dataset from Kaggle. The raw CSV files are not included in this repository due to their large file size.

🔗 Download the dataset here: IEEE-CIS Fraud Detection — Kaggle

The dataset contains two files that are merged on TransactionID:

• train_transaction.csv — transaction-level features and the isFraud target label
• train_identity.csv — identity and device information per transaction

After downloading, place both files inside the Dataset/ folder before running the notebook.

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🛠️ Tools & Libraries Used

Tool	Purpose
Python 3.x	Main programming language
Google Colab	Notebook development environment
Pandas / NumPy	Data loading and manipulation
LightGBM	Primary classifier
XGBoost	Comparison model
Scikit-learn	ML utilities, metrics, preprocessing
imbalanced-learn	SMOTE for class imbalance
SHAP	Explainable AI
Optuna	Hyperparameter tuning
Plotly	Interactive visualizations
Streamlit	Live fraud operations dashboard
Matplotlib / Seaborn	Static charts and heatmaps

Install all dependencies:

pip install -r requirements.txt

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🚀 How to Run This Project

Option 1 — Open Notebook in Google Colab

1. Go to colab.research.google.com
2. Click File → Open Notebook → GitHub
3. Paste: https://github.com/smohan-21/fraud-detection-system-with-explainable-ai
4. Select Analysis.ipynb
5. Run the first cell to install dependencies:

!pip install -r requirements.txt

Option 2 — Run the Streamlit Dashboard Locally

# Clone the repository
git clone https://github.com/smohan-21/fraud-detection-system-with-explainable-ai.git
cd fraud-detection-system-with-explainable-ai

# Install dependencies
pip install -r requirements.txt

# Launch the dashboard
streamlit run Dashboard/app.py

Or visit the live deployed version directly: (https://fraud-detection-system-with-explainable-ai-5rtlqu5k7cchtzgsfee.streamlit.app/)

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📊 Key Outputs

Output	Location
Full analysis notebook	Analysis.ipynb
Model performance comparison	Model_Comparison.png
SHAP global summary plot	Shap_Summary.png
All visualizations	Chart/ folder
Live dashboard app	Dashboard/ folder
Business insights report	Summary.pdf
Sample data for dashboard	sample_data.csv

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👤 Author

Mohan S AI & Data Analyst Intern — Week 3 & 4 Project GitHub: @smohan-21

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📄 License

This project is built for internship and educational purposes.