Step by step guide to editing queries in Power BI using the Query Editor for data transformation

Excercise 2. Air Quality Data Analysis: Monitoring Pollution Levels
Monitoring the air quality in various cities and polluting trends over time was the objective.
Data Source:
•Dataset: Air Quality Data (OpenAQ)
•Download link: Air Quality Data
Solution Steps:

1.Download the Dataset:
oDownload the data from OpenAQ - Air Quality.

2.Import Data into Power BI:
oOpen Power BI Desktop.
oGo to Home > Get Data > Web.
oPaste the URL: https://raw.githubusercontent.com/openaq/openaq-fetch/master/data/australia/2020-11-01.csv and click OK.
Or
https://github.com/openaq
oClick Load to bring the data into your Power BI workspace.

3.Create Visualizations:
oLine Chart for PM2.5 Levels: Drag Date to the Axis and Value to the Values. Filter for PM2.5 to track this specific pollutant’s trends over time.
oBar Chart for Air Quality by City: Drag City to the Axis and Value to the Values. Filter the Parameter field to show PM10 and NO2. This will display the air quality levels for different cities.
oScatter Plot: Use a scatter plot to compare the levels of various pollutants. Drag Value to both the X-axis and Y-axis, and use Parameter as the legend to differentiate between different pollutants.

4.Analysis:
oTrack the trends of PM2.5 levels and identify cities with high pollution.
oCompare different pollutants and see how they impact air quality across various locations.
oDiscover which cities are most affected by specific pollutants and how pollution fluctuates over time.

Excercise 3. Global Population Growth Analysis
Objective: Analyze and visualize population growth across different countries over time.
Data Source:
-Dataset: World Population Data
-Download Link: World Population Data
Step-by-Step Solution:

1.Download the Dataset:
oDownload the population data from the following link: World Population Data.

2.Import Data into Power BI:
oOpen Power BI Desktop.
oGo to Home > Get Data > Web.
oPaste the URL: https://raw.githubusercontent.com/datasets/population/master/data/population.csv into the field and click OK.
oPower BI will automatically load the data for you to start working with.

3.Create Visualizations:
oBar Chart for Population by Country: Create a bar chart by dragging Country to the Axis and Value (population) to the Values. Filter for Year 2020 to display the population for each country in that year.
oLine Chart for Population Growth: Track population growth over time by dragging Year to the Axis and Value (population) to the Values. Filter the chart by a specific country to observe its growth trend.
oMap Visualization for Population Distribution: Use the Map visualization to display the population distribution worldwide. Drag Country to the Location field and Value to the Size field.

4.Analysis:
oIdentify which countries have the largest populations in 2020.
oTrack the population growth trends for specific countries (e.g., China, India) over the years.
oVisualize the global distribution of population using the map to see the relative population sizes across continents and countries.

Conclusion
These practical exercises will help you build useful skills in Power BI while analyzing real-world datasets. Following these steps will give you a better understanding of how to work with data in Power BI and build meaningful visualizations.