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RafaelKarcz/README.md

Hi, I'm Rafael Karcz 👋

I'm a data-driven analyst who loves turning messy, real-world problems into clean, actionable insights. I care about systems, small improvements, and tools that scale.

Current focus ⚡️

I'm honing my data skills with a bias toward practical business impact. Long-term, I want to use data to drive meaningful, positive change. Right now I'm working through the Python Developer path on JetBrains’ Hyperskill and a Coursera AWS Fundamentals specialization.

Background 🎓

I completed my Economics degree two years ago and have been deepening my toolkit across Python, SQL, and analytics engineering since.

What I believe 👨🏻‍💻

I love coding and crafting efficient data workflows in service of sustainable development, and I’m a proponent of open-source software; you’ll find projects here showcasing Python, SQL, Power BI, and Bash.

For data visualization, see both:

  • My Power BI report repos here on GitHub, and
  • Selected work on Tableau Public

Skills & tools 🧰

At a glance:
Power BI | SQL | Python | Data Modeling (Star Schema) | DAX | Power Query/M | ETL | MySQL | Excel (Power Query/Power Pivot) | Git/GitHub | JupyterLab | VS Code | WSL (Bash) | Linux | Anaconda | REST APIs | Looker Studio

Full skills (expand)

Business Intelligence
Power BI (Data Modeling/Star Schema, DAX, Power Query/M, Drillthrough, Bookmarks, Field Parameters) | Power BI Service (Workspaces, Dataflows, RLS, Incremental Refresh, Gateways, Pipelines, Parameters)

SQL & Databases
SQL (Joins, Window Functions, CTEs, Aggregation, Subqueries) | MySQL | Basic Query Tuning

Excel (Advanced)
Power Query (Get & Transform) | Power Pivot | PivotTables | SQL-Connected Pivots (CRM-to-Excel)

Python (Analytics)
pandas | NumPy | Matplotlib | Scripting & Automation | Web Scraping (BeautifulSoup) | SQLAlchemy

Data Engineering / ETL
Source-to-Model Pipelines | Data Cleaning & Shaping | CSV/Excel/Database Ingestion

Tools & Platforms
Git | GitHub | Looker Studio | Tableau | JupyterLab | VS Code | WSL (Bash) | Linux | Anaconda | REST APIs

Methods
KPI Design | A/B Testing | Trend/Variance Analysis | Cohort Analysis | Regression & Inference | Hypothesis Testing | Research Design (Sampling, Interviews) | Stakeholder Alignment | Process Mapping | Data Storytelling | Agile

Project highlights 🚀

  • Power BI — AdventureWorks
    Star schema, robust DAX measures (AOV, T12M, Time Intelligence), KPI tiles, drill-throughs, and clean UX; focused on performance and business storytelling.

  • Python — Investor Calculator
    CLI/Notebook tool to evaluate investment scenarios (lump-sum vs DCA, fees, taxes, FX), with charts and sensitivity analysis.

  • SQL — Expense Tracker
    End-to-end SQL project modeling expenses: clean, categorize, and aggregate transactions; views for monthly burn, vendor analysis, and rolling 12-month trends.

  • Bash — True or False (mini-game)
    Lightweight Bash project demonstrating CLI UX patterns, input validation, and file I/O.

Want a deeper dive? Explore more in my GitHub repos and portfolio.

Ask me about 📬

  • Data analysis & visualization
  • SQL modeling and data cleaning
  • Python automation & scraping
  • Building practical, readable dashboards
  • Zen + small habits that compound

Fun fact 🌍

I’ve lived in enough places that the whole world feels like home. These days, I’m based in Tokyo.

Connect

Pinned Loading

  1. PowerBI_AdventureWorks PowerBI_AdventureWorks Public

    Advanced Power BI Adventure Works sales analytics (PBIX + data) with dynamic UX and an icon library.

  2. ExpenseTracker ExpenseTracker Public

    A set of SQL queries designed to analyze income and expenses, categorize spending, and track financial trends through various advanced operations like running totals, grouping, and filtering.

  3. ArticleScraper ArticleScraper Public

    A Python web scraping tool that retrieves articles from a specified webpage, filters them by type, and saves the content into organized directories.

    Python

  4. InvestorCalculator InvestorCalculator Public

    InvestorCalculator is a Python-based tool that helps manage and analyze company financial data, providing key financial metrics and insights for investors.

    Python

  5. LearningProgressTracker LearningProgressTracker Public

    The Learning Progress Tracker project is a Python-based command-line application designed to track and manage student progress across various courses. It allows adding students, updating their cour…

    Python

  6. True-or-False-Game True-or-False-Game Public

    A Bash-based interactive True or False game that fetches questions from an API, tracks player scores, and provides a fun gaming experience with score management.

    Shell