Carlos J. Gil Bellosta, Developer in Madrid, Spain
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Carlos J. Gil Bellosta

Verified Expert  in Engineering

Data Scientist and AI Developer

Madrid, Spain
Toptal Member Since
February 10, 2021

Carlos has 17 years of experience in data science in domains such as IoT, financial risk, credit scoring, churn analysis, biotechnology, and eCommerce. His international industry experience is backed by completing all courses toward a PhD in statistics and a master's and bachelor's degree in math. In addition to being an active contributor to the ecosystem of R packages, Carlos shares his expertise by giving talks and teaching data science at universities and business schools.


R, Python, Statistics, Data Science, eCommerce, ETL, Machine Learning, GPT...
R, Python, Teradata, SQL, Spark, Data Science...
Statistics, R, SQL, Python, ETL, JSON, Time Series Analysis, Data Analytics




Preferred Environment

Linux, R, Python, Scikit-learn, Statistics, Bayesian Statistics, SQL, Data Science, RStudio Shiny, Forecasting

The most amazing...

...project I've developed involved creating the statistical engines behind lab data analysis workflows for a leading medical equipment manufacturer.

Work Experience


2015 - PRESENT
  • Created models to track and estimate flu, heat waves, and COVID-related deaths for the Spanish Ministry of Health.
  • Developed a system to optimize eCommerce campaigns, thereby minimizing customer impacts while maintaining an expected level of profitability.
  • Created a system to analyze customer flow in physical retail stores, which has been implemented in several big-name merchants with hundreds of stores in Spain.
  • Developed a churn analysis tool for a major security systems company in Spain.
  • Taught master's level courses in R and statistics in several universities (IE, EOI, UC3M, Complutense University of Madrid, and UNIR) and business schools (EAE and KSchool) in Spain, Peru, and Costa Rica.
  • Gave talks about machine learning, statistics, and big data in Spain, Colombia, Costa Rica, and Peru.
  • Developed models to predict product sales at a large dairy producer and a stock management and production optimization system.
  • Created tools and models to measure and improve keyword performance in Google Ads.
  • Developed tools and models to measure and improve the performance of keywords, ads, and targets for eCommercers on the Amazon platform.
  • Created tools and models to optimize the stock on Fulfillment by Amazon (FBA) for sellers on the platform.
Technologies: R, Python, Statistics, Data Science, eCommerce, ETL, Machine Learning, Generative Pre-trained Transformers (GPT), Natural Language Processing (NLP), GPT, RStudio Shiny, Databases, JSON, Time Series Analysis, Data Analytics, Recommendation Systems

Senior Data Scientist

2014 - 2015
  • Developed tools to monitor the performance and engagement of new customers to the platform.
  • Created models to classify visits to the platform according to their browsing behavior, using novel techniques borrowed from natural language processing theory.
  • Played a key role in developing a company-wide platform to automate A/B testing and generate homogeneous campaign performance measures for all stakeholders.
  • Created tools to improve the performance of marketing campaigns.
  • Developed and maintained tools to detect fraud and illegitimate behavior of users in the platform.
Technologies: R, Python, Teradata, SQL, Spark, Data Science, Natural Language Processing (NLP), GPT, Generative Pre-trained Transformers (GPT), Machine Learning, OpenStack, Fraud Prevention, A/B Testing, eCommerce, Databases, Time Series Analysis, Data Analytics, Recommendation Systems

Statistical Consultant

2010 - 2014
  • Participated in a large-scale ETL project in a major Spanish bank as part of the performance optimization team.
  • Developed the statistical engine for several laboratory data analysis workflows for a leading manufacturer of medical equipment.
  • Played a key role in the creation and first projects of one of the leading data analysis and data science working groups in Spain within BBVA, the global financial services group.
  • Assisted in the development of the R community in Spain, becoming the co-founder and serving as the first president of the association of Spanish R users.
  • Created a pioneering model, using the network of transactions among SMEs to predict their credit risk.
Technologies: Statistics, R, SQL, Python, ETL, JSON, Time Series Analysis, Data Analytics

Senior Consultant

2009 - 2010
Everis Spain, S.L.U
  • Developed part of the internal analysis code for a financial risk management tool sold to several international banks.
  • Introduced modern code development standards for my team.
  • Created models for financial risk, especially credit risk for mortgages.
Technologies: R, SQL, MATLAB, Data Science, A/B Testing, Risk Models, Credit Risk, Market Risk

Statistical Consultant

2005 - 2009
  • Implemented a SAS-based tool for Basel II compliance at Krung Thai Bank (KTB) in Thailand while serving as the main technical expert.
  • Implemented a SAS-based tool for Basel II compliance at Barclays Bank, London, as a member of a team of technical experts.
  • Provided technical support in the implementation of SAS risk management tools in several banks in Croatia, Belgium, and Pakistan.
Technologies: R, SAS, Risk Models

SAS Consultant

2004 - 2004
Bank of Spain (via Soluziona)
  • Maintained the SAS-based technological infrastructure in the bank supervision department at the Bank of Spain.
  • Improved the performance of the SAS code in the bank supervision department at the Bank of Spain.
  • Provided SAS support to several SAS projects within the Bank of Spain.
Technologies: SAS, SQL, Risk, Finance

SAS Consultant

2003 - 2004
  • Provided technical support in the sales process for SAS-related risk management products.
  • Developed models to assess the market risk of diverse portfolios, including financial and real assets in energy firms.
  • Beta tested products for risk management during early development within SAS.
Technologies: SAS, Risk, Market Risk, Credit Risk, ETL

HR Dashboard for a Global Consultancy Company

A global consultancy was interested in building an HR dashboard to provide information on its hiring funnel, which I created and maintained. I created a database that integrated data from different onboarding systems, integrated them in a combined database, and created dynamic reports and dashboards for the global, distributed HR team.

Optimization of Email Marketing Campaigns

I created models to estimate openings, clicks, and conversions on email marketing campaigns at the customer level. Then I created a system to optimize the weekly number of sendings to minimize the number of contacts while maintaining the required profitability level of the individual campaigns.

COVID-19 Mortality Model in Spain

An official application sponsored by the Ministry of Health to track COVID-related mortality in Spain. I developed the statistical models behind the application, which are based on a GAM Poisson model that includes controls for heatwaves, cold spells, age, sex, and other covariates.


R, Python, SQL, Snowflake, SAS


RStudio Shiny, Spark


Scikit-learn, Caret, XGBoost, Pandas


Data Science, ETL, Linear Programming


Linux, Windows, H20, Google Cloud Platform (GCP), OpenStack, Kubernetes


Databases, JSON, Teradata


Statistics, Bayesian Statistics, Programming, Time Series, Machine Learning, A/B Testing, Forecasting, Data Analysis, Data Engineering, Time Series Analysis, Data Analytics, Recommendation Systems, eCommerce, Natural Language Processing (NLP), Email Marketing, Finance, GPT, Generative Pre-trained Transformers (GPT), Epidemiology, Risk Models, Risk, Market Risk, Credit Risk, Biostatistics, Fraud Prevention


Jenkins, MATLAB

Industry Expertise


1998 - 2003

Completed Ph.D. Coursework (ABD Status) in Statistics

Washington University in St. Louis - St. Louis, MO, USA

1997 - 1998

Master's Degree in Mathematics

Washington University in St. Louis - Saint Louis, MO, USA

1992 - 1997

Bachelor's Degree in Mathematics

University of Zaragoza - Zaragoza, Spain

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