Samuel Maina

Available to hire

Data Analyst skilled in SQL, Python, Excel, and Power BI. I build clean databases, transform raw data into reliable insights, and create interactive dashboards that help businesses make better decisions.

About

Data Analyst skilled in SQL, Python, Excel, and Power BI. I build clean databases, transform raw data into reliable insights, and create interactive dashboards that help businesses make better decisions. Available for freelance projects and data analytics collaborations.

  • Joined October 2026

Industry experience

  • Software & Internet

Projects · 3

Retail businesses face a tough balancing act: missing real fraud drains revenue, while excessive security flags can disrupt legitimate customers. I built an end-to-end fraud analytics project using 100,000 retail transactions to uncover fraud patterns and risk exposure across payment methods, merchant categories, account age, transaction behavior, and locations. The Data Challenge & Solution Data profiling revealed that the native fraud-risk score was broken, flatlined at 0.0 across all records, while two location-related fields contained duplicate information. Instead of fabricating a risk score, I engineered a transparent Risk Level classification (Low, Medium, High) using behavioral security indicators including velocity, proxy/VPN usage, and high-risk devices. Technical Execution SQL: Cleaned data, removed duplicates, standardized formatting, and handled null values. Power BI: Built an interactive 3-page dashboard: Overview, Detection, and Recommendations. Key Findings • Medium Risk transactions carried the highest financial exposure at approximately $7.1M, followed by High Risk at $3.3M. • Fraud was concentrated in lower transaction-value brackets ($0–$500). • Domestic transactions accounted for 66.8% of activity, versus 33.2% international. • Analysis covered payment methods, merchant categories, account age, transaction frequency, velocity indicators, and countries.

  • Data Analyst
  • Data Visualizer

Retailers often collect large amounts of sales and inventory data but struggle to turn it into clear decisions around stock, demand, and revenue performance. I built an end-to-end retail analytics solution using Python, MySQL, and Power BI. With Python and Pandas, I cleaned and prepared the raw dataset, handling missing values based on their business meaning rather than blindly replacing them. The data was then analyzed in MySQL to explore revenue, units sold, inventory, discounts, categories, regions, and seasonal performance. The final result was an interactive Power BI dashboard designed for quick business monitoring. It includes KPI cards for revenue, total stock, demand fulfillment, total products, and average discount, alongside sales by category, monthly seasonal performance, regional revenue and units sold, inventory by demand forecast, and seasonal distribution.

  • Data Analyst
  • Data Visualizer

Developed an end-to-end Business Intelligence solution for the private security industry to improve operational visibility and decision-making. The project involved data cleaning and transformation using Python, relational database design in MySQL, SQL data management, and interactive dashboard development in Microsoft Power BI. The final solution consists of four dashboards covering Executive Overview, Workforce Analytics, Operations Analytics, and Commercial Analytics.

  • Data Analyst
  • Data Visualizer

Work experience

Data Analyst · FiverrMar 2025 – Present · 1 yr 9 mos

Delivered custom data processing, SQL database querying, and interactive Power BI dashboards for global clients across various domains including retail inventory, risk modeling, and operational performance tracking.

Education

Bachelor of Science in Criminology · Murang'a University2025 – 2029

Certifications and awards

Cisco Data Analytics Essentials2026

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