Ujaval Gandhi

ujaval@spatialthoughts.com

Introduction to QGIS

Data Normalization

CC BY-4.0

Types of Maps

• Reference Map
• Helps the readers understand the geographic area
• Topographic map, Political Map etc.
• Thematic Map
• Focuses on the distribution of a specific topic
• Choropleth map, heatmap, dot density map

Choropleth Maps

• Choropleth Maps are the most common type of thematic maps
• The term 'choropleth' is derived from the Greek choros for region, and plethos, for magnitude.
• Represent data by changing the color based on the value
• Ideal for data like rates, densities or percentages
• Not recommended for absolute values
• Using absolute values will over-emphasize large features
• You must always ‘normalize’ the data when creating choropleth maps

Example:

Mapping Demographic Data

Number of Literate Persons in Each Region

10

10

5

15

Number of Literate Persons in Each Region

0-5

5-10

>10

10

10

5

15

Let’s normalize the data

Number of Literate Persons in Each Region

10

10

5

15

Population in Each Region

20

15

5

45

Literacy Rate in Each Region

10 / 15 = 66%

10 / 20 = 50%

5 / 5 = 100%

15 / 45 = 33%

Literacy Rate in Each Region

10 / 15 = 66%

10 / 20 = 50%

5 / 5 = 100%

15 / 45 = 33%

< 50%

50-75%

>75%

How to normalize your data?

• Calculate density
• Population / Land Area
• Calculate rate
• COVID19 cases / 100,000 population
• Unemployed persons / total working-age population
• Calculate percentage
• Urban population / total population
• COVID Delta variant cases / all new COVID cases