Introduction to Power BI
Power BI is a tool used to transform messy data into interactive insights that support business decision. The process involves three key stages: cleaning and preparing data, building calculations using DAX, and designing dashboards that communicate insights clearly.
Cleaning Data
Power Query is a tool that allows data connection, transformation, and loading.
First we need to load the Data to Power BI:
Open Power BI Desktop > Get Data > Excel > Select File > Load Sheet
Then Transform Data:
Click Transform Data.
Power query is used in transforming raw data through:
- Remove duplicates and irrelevant columns: Select the columns > Remove Duplicates
- Change Data Types: Texts, numbers, dates, currency
- Handle Errors.
- Standardize formats. -Filtering irrelevant records.
DAX Functions
DAX (Data Analysis Expressions) is a formula language used in Power BI to create
calculations and data analysis logic.
DAX is used to build measures, calculated columns, and calculated tables that help transform raw data into meaningful insights.
Examples:
SUM
Adds all numeric values in a column.
Total Profit = SUM('Kenya Crops'[Profit (KES)])
AVERAGE
Calculates the mean of a numeric column.
Average Revenue
Average Revenue = AVERAGE('Kenya Crops'[Revenue (KES)])
We use New Measure if you expect a single output while we use New Column if the expected output is multiple rows corresponding to the data.
Dashboard Creation
A Power BI dashboard should answer questions instantly, not just display numbers.
Effective dashboards:
- Highlight KPIs at the top
- Use the right visual for each question
- Allow filtering using slicers
- Tell a clear story
Example
Conclusion
Conclusion
Power BI enables analysts to bridge the gap between raw data and strategic decision-making. Power BI is more than charts and visuals. Analysts use it to:
Clean and structure messy data.
Build models that reflect real business processes.
Apply business logic using DAX.
Deliver dashboards that support confident decision-making.
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