• Hi,
    I'm David

    Data Analyst

    Transform messy data into meaningful insights by identifying trends and patterns for better decision-making.

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About Me

Who Am I?

I am a mathematics teacher transitioning into data analysis, bringing extensive experience in analytical thinking and problem-solving. As head of the academic department, I've analyzed student test scores and managed databases, which has sharpened my skills in identifying patterns and effectively communicating findings.

I've completed real-world data projects, gaining experience in data wrangling and cleaning with SQL and Python, and creating visualizations using Power BI, Excel, and Google Looker Studio. My passion lies in uncovering patterns in complex datasets and turning them into actionable insights that drive decision-making.

Eager to fully transition into a data analyst role, I am committed to applying my expertise in statistics, programming, and visualization to deliver impactful solutions. I am currently enhancing my skills in Tableau and continuously advancing my knowledge as a data professional.

To learn more about my experience and skills, please review the tools I've used and download my CV to see how I can add value to your team!.

Python

Jupyter Notebook

Looker Icon

Google Looker

Power BI Icon

Power BI

VS Code

Tableau

Excel

R

My Specialty

My Skills

My expertise spans both technical and interpersonal domains, allowing me to solve complex challenges with precision and adaptability. While exploring a Kaggle SQLite dataset, I meticulously validated relationships, filtered anomalies, and cross-verified aggregations using Python, revealing actionable trends. In analyzing student performance, I transformed raw exam data into compelling insights with Power BI, creating clear visualizations and structured reports that empowered stakeholders to make data-driven decisions confidently.

Working with inconsistent soccer data, I addressed missing values through data cleaning and interpolation, restoring accuracy to performance trends despite incomplete records. Beyond analysis, I managed complex projects involving SQL, Python, and Power BI, streamlining workflows with structured timelines, phase prioritization, and automation. While examining student exam results, I identified grade discrepancies and rigorously validated calculations, ensuring precise performance predictions.

Uncovering trends, simplifying insights, and managing intricate workflows are at the heart of what I do. I thrive on transforming raw data into meaningful narratives that drive informed decisions. My work is driven by a strong foundation in these key skills:

Hard Skills

Soft Skills

Critical Thinking

75%

Problem-Solving

80%

Communication

70%

Attention to Detail

85%

Time Management

75%
Portfolio

Recent Work

  • SQL
  • Python
  • Excel
  • Power BI
Python project showcasing performance table

SQL Project

This project analyzes a Kaggle SQLite dataset using SQL and Python libraries. It applies JOINs, subqueries, and CTEs for data cleaning, EDA, and aggregations, extracting meaningful patterns and visualizing key insights.

LookerStudio Dashboard Article
Insights

Aircraft Revenue,the top three revenue-generating airports are Domodedovo (1,986M), Sheremetyevo (1,579M), and Tolmachevo (799M), highlighting key destinations.

Sales Trends, July had the highest ticket sales at 63%, followed by August (34%), maximizing revenue across economy, business, and comfort classes.

Ulyanovsk East Airport had the most delays, with Ignatyevo and Lipetsk also experiencing over 20-minute average departure delays.

Peak travel days saw the highest bookings, aligning with the most popular flight hours and routes.

Python project showcasing cluster ofensive playing style

Python Project

This project analyzes Kaggle's soccer database, uncovering insights into Europe's top leagues (2008/09-2015/16). Using Pandas for data wrangling, Matplotlib & Seaborn for visualization, and ML models, it explores team performance, player development, peak ages, and playing styles, blending analysis and storytelling to reveal hidden patterns in the beautiful game.

Tableau Dashboard Github Article
Insights

The goal distribution across seasons was relatively normal, indicating strong offensive play.

Napoli (Serie A) showed the most improvement over the period, with a YoY of +0.947 points.

The peak performance age falls within the 24-27 age group.

Key strategies include fast build-up play, wide defensive play, and chance creation through passing and crossing.

Offensive and balanced playing styles are the most effective in achieving a positive GD.

Stamina and sprint speed attributes declined with age.

Excel project showcasing performance table

Excel Project

This Excel project analyzed 2023 KCSE student performance across 19 schools, comparing results with 2022 and 2021. Using an Excel-based data model, advanced formulas, and pivot tables, I generated dynamic dashboards, revealing insights on grades, gender performance, rankings, deviations, and subject trends for educational improvements.

Dashboard Article
Insights

13% improvement in students scoring C+ and above in 2023, reflecting a positive trend in higher-grade achievement.

50% increase in students scoring grade E in 2023 compared to 2022, highlighting an area needing targeted support.

Overall, 15% of students attained C+ or higher, with girls at 17% and boys at 13%, showing a slight performance advantage for girls.

Top-performing subjects included Computer Studies (8.51), Home Science (8.32), and Kiswahili (6.54), while Chemistry (2.57), Mathematics (2.55), and Agriculture (2.49) scored the lowest.

Power BI project showcasing performance table

Power BI Project

This Power BI project analyzed 242 students' performance across 14 subjects in a six-streamed school, comparing July and October exams. Using DAX calculations and multiple data sources, I built dynamic and interactive dashboards that uncovered insights on subject, stream, and grade performance, predicting KCSE outcomes.

PowerBI Dashboard Article
Insights

The school achieved a mean score of 6.65 in the October Series, falling slightly below the target mean of 7.29, indicating room for improvement before KCSE.

Students scoring quality grades C+ or higher increased by 34% in October Series, with 50% achieving this benchmark compared to only 16% in the July Series.

An impressive 99% of students showed improvement in their grades and mean points, while only 1% maintained their July Series results, highlighting significant academic progress overall.

Only 64% of subjects met their set targets.

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Education

Academic Journey

Education has been the cornerstone of my professional journey, equipping me with a strong foundation in statistics and STEM. Highlighted below is an overview of the key academic institutions and programs that have shaped my skills and career path.

Data Analyst

Datacamp | 2023 - 2024

Data Analyst in Power BI
  • Turned raw data into compelling insights using Power BI by mastering data visualization techniques, DAX formulas, and advanced measures.
  • Created compelling visuals with diverse chart types, enhancing the clarity and impact of data presentations.
  • Developed interactive dashboards with slicers, filters, and DAX calculations to provide real-time insights and facilitate data exploration.
Associate Data Analyst in SQL
  • Mastered SQL queries (SELECT, JOIN, WHERE) to retrieve and manipulate data, unraveling the secrets hidden in databases.
  • Became proficient in using various JOIN operations (INNER JOIN, LEFT JOIN, RIGHT JOIN) to combine and relate tables, effectively matchmaking data.
  • Leveraged the power of the WHERE clause and subqueries to filter and locate specific data, extracting meaningful insights from complex datasets.
  • Utilized window functions (ROW_NUMBER, RANK, PARTITION BY) to perform advanced calculations across rows, providing deeper analytical insights.

Data Analysis with Python

FreeCodeCamp | 2022 - 2023

  • Received in-depth training on data analysis with Python, covering key topics like EDA, visualization, and data manipulation. Gained practical experience by working on projects that applied these skills to real-world datasets.
  • Developed hands-on experience and skills with analytics tools for data manipulation, effectively handling and analyzing CSV files.

Data Analyst Nanodegree

Udacity | 2022

  • Mastered data wrangling and statistical inference, utilizing Jupyter Notebook for interactive coding. Gained hands-on experience using the Twitter API, Beautiful Soup for web scraping, and handling complex data formats, including Excel, text, and JSON files.
  • Developed advanced data cleaning and storytelling skills, utilized Pandas, Matplotlib, and Seaborn libraries to create compelling slide decks, and crafted engaging data stories.

Programming Essentials in Python

Cisco Networking Academy® | 2022

  • Comprehensively learned essential Python programming concepts, including variables, data types, loops, functions, file processing, and error handling. This foundational knowledge enables the creation of efficient and robust Python scripts.
  • Developed the practical ability to write and execute Python scripts effectively, applying learned concepts to solve problems and automate tasks, demonstrating advanced skills in programming with Python.

B. Ed Science (Statistics Major)

Kenyatta University | 2006 - 2010

  • Foundational Journey: Completed a Bachelor's Degree in Education Science with a major in Statistics, gaining a strong foundation in probability distributions, hypothesis testing, and data analysis.
  • Advanced Data Science Skills: Acquired expertise in statistical distributions, regression models, time series analysis, experimental designs, and sample surveys, enhancing the ability to predict trends and make data-driven decisions.
What i do?

My Expertise

Data Insights

Analyze complex datasets with SQL, Python, and R and create compelling and insightful visualizations using Matplotlib, Seaborn, Power BI, and Tableau to drive data-driven decisions.

Data Exploration (EDA)

Transform, clean, and explore data to uncover oddities, trends, patterns, and outliers, ensuring high-quality data for more in-depth analysis.

Data Wrangling

Wrangle, process, and integrate data from diverse sources, including APIs, web scraping, SQL, and file formats such as Excel, text, CSV, and JSON, to create a cohesive and reliable dataset.

Database Management

Design database, write complex SQL queries, and optimize performance to ensure efficient data retrieval, management, and analysis across rational database systems.

Dashboard Development

Develop interactive dashboards by designing visualizations, integrating data from multiple sources, and optimizing performance to effectively display key metrics for informed decision-making.

Predictive Analytics

Apply statistical techniques and build predictive models, such as regression and classification, to solve real-world problems and uncover actionable insights from complex data.

Read

Recent Blog

Bivariate chart by davidportfolio
October 6, 2024 | Data Analysis |

Unlocking Insights with Bivariate Visualization

Explore the power of paired insights and lay the groundwork for deeper analysis.

Multivariate chart by davidportfolio
October 6, 2024 | Data Analysis |

Exploring the Depth of Multivariate Charts

Dive into a gateway to uncovering complex relationships and patterns in data.

Get in Touch

Contact

Message Us

Get in Touch

Thank you for visiting my portfolio! I am always open to new opportunities and collaborations. If you have any questions or would like to discuss a project, feel free to get in touch.

  • Mombasa, Shika Adabu, KE 80110
  • +254 724438296
  • dave.owino@yahoo.com