Log inSign up free
  • Home
  • Profile
  • Jobs
    • Applications
    • Career
    • Resume
    • Cover letters
  • Content
    • Posts
    • Media
  • Messages
  • Analytics
    • Overview
    • Pages
  • Portfolio
  • More tools
    • Hiring
  • Settings
All jobs
SSSigma Software logo

Sigma Software

Warsaw, pl

Senior Data Scientist.

FULL TIMEREMOTESENIOR LEVELDATA & ML
  • Build and improve censored bid-landscape models to estimate clearing-price distributions from partially observed auction data
  •  Develop real-time win probability estimation models responsive to bid pricing dynamics
  • Design and implement hierarchical lift estimation models with confidence-bound-based selection strategies
  • Build conversion propensity models using sparse, delayed, and aggregate-only labels
  • Develop look-alike audience modeling approaches using positive-unlabeled learning and embedding-based nearest-neighbor techniques
  • Implement advertiser-level calibration strategies while independently monitoring ranking and calibration quality
  • Design robust offline evaluation frameworks using inverse-propensity scoring, doubly-robust estimators, and importance reweighting
  • Define exploration strategies and propensity logging approaches to ensure reliable downstream correction and evaluation
  • Develop constrained optimization mechanisms for campaign objectives, pricing constraints, and volume targeting
  • Contribute to data diagnostics, capability assessments, and evidence-based model recommendations
  • Collaborate with the Customer team during post-launch tuning and performance validation cycles
  • Prepare technical documentation and knowledge transfer materials for the Customer’s internal data science team
  • Participate in architecture discussions and contribute to scalable ML platform design decisions
  • 5+ years of experience in Machine Learning or Data Science with production-grade models measured against business KPIs
  • Strong Python skills including numpy, pandas, and scikit-learn
  • Strong SQL skills and experience working with large-scale datasets
  • Deep practical experience with XGBoost, LightGBM, or CatBoost
  • Strong understanding of regularization, calibration methods, and categorical feature handling
  • Strong knowledge of probability, statistics, confidence intervals, and statistical power analysis
  • Experience with feature engineering for structured and behavioral datasets
  • Hands-on experience with Spark or PySpark
  • Practical knowledge of experimentation frameworks and A/B testing methodologies
  • Experience with advanced validation approaches including temporal splits, leakage detection, drift analysis, and slice-based metrics
  • Understanding of explainability techniques such as SHAP and permutation importance
  • Upper-Intermediate English level or higher

WILL BE A PLUS

  • Experience in AdTech modeling including CTR/CVR prediction, bid-landscape modeling, audience segmentation, and RTB mechanics
  • Experience working with sparse, delayed, or censored labels
  • Knowledge of attribution modeling, survival analysis, and positive-unlabeled learning
  • Practical experience with counterfactual and off-policy evaluation techniques
  • Understanding of calibration methods including isotonic regression and Platt scaling
  • Experience with hierarchical, empirical-Bayes, or partial-pooling models
  • Knowledge of constrained or multi-objective optimization approaches
  • Experience with uplift modeling and causal inference methods
  • Experience with Vertex AI or similar managed ML training environments
  • Publications, competitive modeling achievements, or open-source contributions related to Machine Learning or AdTech

PERSONAL PROFILE

  • Strong analytical and problem-solving skills
  • Ability to work effectively in a highly data-driven environment
  • Strong communication and stakeholder management abilities
  • Ability to explain complex modeling decisions to technical and non-technical audiences
  • Proactive mindset with strong ownership mentality
  • Attention to detail and scientific rigor in experimentation and evaluation
Pay
Not stated
Where
Warsaw, pl
Work
Remote
Type
Full time
Posted
22 Oct, 2026
Apply on the original postingSign in to apply

Unverified board

more at Sigma Software.

22 Oct, 2026

Sigma Software

Sound Producer

SSSigma Software logo
  • Part time
  • Remote

Kyiv, ua

Remote

Details
22 Oct, 2026

Sigma Software

GameDev Internship

SSSigma Software logo
  • Internship
  • Intern
  • Remote
  • Engineering

Kyiv, ua

Remote

Details
22 Oct, 2026

Sigma Software

Middle Java Developer

SSSigma Software logo
  • Full time
  • Remote
  • Engineering

Brasília, br

Remote

Details

similar roles.

22 Oct, 2026

Canals

Machine Learning Engineer

CACanals logo
  • Full time
  • Remote
  • Data & ML

Bogota +4

Remote

Details
22 Oct, 2026

Kepler Group

Senior Analyst Data Strategy & Analytics

KGKepler Group logo
  • Senior level
  • Hybrid
  • Data & ML

San Jose, Costa Rica

Hybrid

Details
22 Oct, 2026

Kepler Group

Analyst Data Strategy & Analytics

KGKepler Group logo
  • Hybrid
  • Data & ML

San Jose, Costa Rica

Hybrid

Details
21 Oct, 2026

Giant Leap Technologies AS

AI-Driven Senior Operations Engineer

GLGiant Leap Technologies AS logo
  • Senior level
  • Data & ML

Helsinki, FI +1

Salary not listed

Details
22 Oct, 2026

ensemblehp

Senior Engineer, Business Intelligence

ENensemblehp logo
  • Senior level
  • Remote
  • Data & ML

Remote - Nationwide

Remote

Details
22 Oct, 2026

ensemblehp

Principal Software Architect- Data Platform, Data

ENensemblehp logo
  • Staff level
  • Remote
  • Data & ML

Remote - Nationwide

Remote

Details