The Data Science Lifecycle & CRISP-DM Process

The Data Science lifecycle is an iterative engineering process for extracting actionable business insights and training predictive models from raw data.

flowchart TD
    P1[1 · Problem Formulation] --> P2[2 · Data Collection & Sourcing]
    P2 --> P3[3 · Data Cleaning & Preprocessing]
    P3 --> P4[4 · Exploratory Data Analysis - EDA]
    P4 --> P5[5 · Feature Engineering]
    P5 --> P6[6 · Model Training & Hyperparameter Tuning]
    P6 --> P7[7 · Model Evaluation & Benchmarking]
    P7 --> EvalCheck{Meets Quality Threshold?}
    EvalCheck -- No --> P4
    EvalCheck -- Yes --> P8[8 · Production Deployment & MLOps]
    P8 --> P9[9 · Observability & Stakeholder Reporting]
    P9 -.->|Continuous Feedback Loop| P1

The 9 Phases of the Process

Phase 1: Problem Formulation

  • Define the business objective or hypothesis.
  • Identify key stakeholders, success metrics (ROI, conversion, latency), and regulatory constraints.
  • Determine project feasibility and scope.

Phase 2: Data Collection & Sourcing

  • Ingest relevant datasets from databases, streaming event buses (Kafka), object stores (S3), and third-party APIs.
  • Evaluate dataset licensing, provenance, and sampling bias.

Phase 3: Data Cleaning & Preprocessing

  • Handle missing values (imputation vs deletion), deduplication, and outlier detection.
  • Data normalization, scaling, and categorical encoding (One-Hot, Ordinal).

Phase 4: Exploratory Data Analysis (EDA)

  • Analyze statistical distributions, variance, skewness, and inter-feature correlations using visualizations.
  • Validate initial assumptions and identify potential confounding variables.

Phase 5: Feature Engineering

  • Construct domain-specific features to maximize model signal-to-noise ratio.
  • Feature selection and dimensionality reduction (PCA, t-SNE) to prevent the curse of dimensionality.

Phase 6: Model Development

  • Select appropriate algorithmic families (tree-based XGBoost/LightGBM, neural networks, linear baselines).
  • Automated hyperparameter optimization (Bayesian search, Optuna) using cross-validation folds.

Phase 7: Model Evaluation

  • Evaluate on unseen holdout test sets using domain metrics: Precision/Recall, ROC-AUC, F1-score, MAE/RMSE.
  • Bias, fairness, and error slice analysis.

Phase 8: Deployment & Maintenance (MLOps)

  • Deploy artifacts via containerized microservices (Triton, KServe, vLLM).
  • Continuous monitoring for covariate data drift and concept drift.

Phase 9: Communication & Insights

  • Deliver executive dashboards and actionable business recommendations.