Free course · Lesson 1 of 5
Data Entry & Cleaning
In this lesson you will
- Structure data as a tidy table
- Clean common data problems
This program focuses on turning business data into decision-ready reports using Excel and Power BI together — distinct from spreadsheet formula mastery alone. It starts where all good analysis starts: clean, reliable data.
- Consistent data entry: Use the same format for dates, categories, and names every time — "Juba", "juba", and "JUBA" will be treated as three different values by most tools.
- Removing duplicates: Use Excel's Remove Duplicates tool (Data tab) to catch accidental repeated entries.
- Handling missing data: Decide deliberately whether to fill, estimate, or exclude missing values — never leave it ambiguous in a shared file.
- Data validation: Set up dropdown lists (Data → Data Validation) for fields like category or region to prevent typos at the source.
Practical Skill: Take a messy sample dataset (inconsistent capitalization, some duplicates, a few missing values) and clean it into a consistent, analysis-ready table.
=== BEFORE (messy) ===Region Sales Datejuba 12000 3/1/2026Juba 8000 2026-03-02JUBA — 03-03-26Wau 15000 2026-03-01 === DATA CLEANING CHECKLIST ===[ ] Standardize text casing (e.g. Proper Case for regions)[ ] Standardize date format throughout (choose one: YYYY-MM-DD)[ ] Decide how to handle the missing "—" value: fill, estimate, or exclude — and document your decision[ ] Remove exact duplicate rows (Data -> Remove Duplicates)[ ] Add data validation dropdowns for Region going forward === AFTER (cleaned) ===Region Sales DateJuba 12000 2026-03-01Juba 8000 2026-03-02Wau 15000 2026-03-01
Practice exercise
Take a messy list of sales with duplicate rows and inconsistent branch names, clean it and write down each change you made.
Key takeaways
- One row per record, one column per field
- Never edit the original data — clean a copy
- Record every cleaning step
Free self-study lesson — no certificate. For the full instructor-led program, see registration options.