Derk-Jan Woltjer - Freelance Datascientist

About

A short introduction!

Hello, my name is Derk-Jan Woltjer, freelance data scientist / data product developer. I work from ‘A to Z’: from data idea, data ingestion, data engineering, model development, to implementation. The goal is always to make data usable. I prefer to develop in small steps, with a continuous check on usefulness. From experience, I know that this approach usually leads to results the fastest.
I am not afraid to look for the missing link within an organization.

Name:

Derk-Jan Woltjer

Year of birth:

1975

Located:

Oss, Noord-Brabant.

Company name:

Datadept.

Services

What I'm good at

Data Analysis

Conducting thorough analyses on datasets to discover patterns, trends, and insights, and converting these into actionable recommendations for decision-making.

Machine Learning

Designing, training, and optimizing machine learning models to make predictions or develop automated solutions. For example, for churn prediction, conversion attribution, and bid-price optimization in online marketing.

Data Engineering

Setting up, managing, and optimizing data models and pipelines for scalable data processing. This can be with platforms like Databricks, but processing via scheduled queries is also possible.

Online Marketing Data

I can work with any structured or unstructured dataset. I have additional experience with online marketing data from platforms such as Facebook, Google Ads, and Google Analytics, for feeding algorithms to optimize performance.

Data Visualization

Designing and creating clear data visualizations to make complex information straightforward and insightful, enabling the extraction of actionable insights. This can take various forms, such as a map, process flow, or dashboard with different visuals.

Product Development

Guiding and executing the complete process from idea to implementation of data products, including concept development, prototyping, and production-ready delivery.

Resume

My professional background

Work Experience

Freelance Datascientist

2022 +3yr.

Data analysis, data science, and data engineering.
ETL development for various data streams, churn model, attribution model, customer profiles, geographical data presentation (GIS), customer journey analysis, campaign effect analyses. Often in collaboration and coordination with marketing and sales specialists. Clients: Deltafiber and Adchieve.com

Data Scientist

Springbok Agency / 2016 +6yr.

Development of various models and tools: Multi Touch Attribution model (MTA), Media Mix Model (MMM), Bid optimizer, Process mining, dashboards, consultancy. Usually using Google Cloud as a platform for solutions. Well-known brands I got to work for include Bol.com, T-Mobile, Essent, Jumbo and ANWB.

Team Lead Business Intelligence

Sligro Food Group / 2010 +5yr.

Guided the transformation from a push-based reporting system to a scalable pull system, expanding the user base from 200 to 500. Staff development. Coordination with the business about information needs, definitions, and reporting formats.