Demographic Composition & Population Features of Cities

Instructor: David Juliao

David has a bachelor's degree in architecture, has done research in architecture, arts and design and has worked in the field for several years.

In this lesson, explore the composition and characteristics of the population of our cities. Examine some basic concepts and important demographics, like age, gender and income and learn about how qualitative and quantitative data is used.

Who Lives in Our Cities?

More than half of the world's population lives in urban areas. That's over three billion people, and, as you might expect, cities are not homogeneous. Some are huge, others are small; some have many young residents while others are retirement destinations; some are poor, others are wealthy. How is all this information collected, and how can we analyze it?

Every city is unique and the population has different characteristics
Collage of cities

In order to understand the population of a city, we need to study its characteristics and composition.

Demographic Composition and Population Characteristics

The population characteristics of a city are the elements that can be used to identify and categorize the people living there, like age, sex, education level, average income, religion, political views and many others.

The demographic composition refers to the proportion or number of people who can be identified with a certain characteristic. The demographic composition provides a mathematical description of the people living in a specific area. For example, 55% of the residents are female, the average age is 27 and 7,500 residents have an income of 15,000 dollars a year or less.

Some Commonly-Studied Demographics

Let's examine some of the most common and important demographics:

Density is the relation between the number of residents and the area covered by the city. It is usually expressed as the number of inhabitants per square mile. More detailed density analyses could include, for example, the density of a minority in a specific neighborhood.

Gender is another common demographic. It studies the male-to-female ratio of a population and is also used to examine the income of women versus that of men, the proportion of college-graduate females and other similar comparisons.

Age provides information about the number of people in a certain age range, like babies, people from 18-24 years or seniors. This data can provide information preferences and trends among age groups and can help policy-makers to orient social programs, like healthcare or child support.

A population pyramid showing the age and gender composition of the people living in San Francisco, CA
Population pyramid

Social class involves several characteristics, like average income, occupation, education level and home sizes, and serves to obtain socioeconomic information.

Ethnicity provides information about the racial or national background of the population and helps to identify possible vulnerabilities among minority groups. In many cities, it is common for members of a minority to locate close to each other, giving origin to areas like Chinatown or Little Italy.

Ethnic composition of the people in New York City
Ethnicity chart

The Data for Analyzing Cities

There are two main types of data you can use to analyze the population of a city: quantitative and qualitative data.

Quantitative data is numerical data that can be transformed into statistics. Basically, any information expressed by numbers, like the number of residents of a certain age, the percentage of unemployment or the number of schools in a district.

This information is usually provided by surveys and censuses. Surveys usually collect information from a certain number of individuals (a sample) and generalize it to the entire population. The census is usually more detailed and involves collecting information from all residents.

Qualitative data is descriptive information about a subject, like the beautiful views of a bay in a city or the usually nice and friendly character of the local residents.

This information often comes from field observations or surveys with open questions. The data is then analyzed to identify common topics. For example, if many people say they don't feel safe in the city, this becomes a topic that might be further examined, maybe by reviewing crime rates and identifying factors that may relate to public safety, like street lighting and drug consumption.

All this information serves many different purposes. It allows you to know more about the place you live in and maybe explore other urban areas if you are going to relocate. It helps industries to identify potential locations for establishing operations or new facilities. The data is also valuable for governments and policy-makers, who can use it to identify issues and design social and economic policies accordingly.

Interpreting Data

Now you know about the data used to analyze the demographics of a city, so let's examine a real-life example.

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