Population Data: Definition, Classification, Estimation and Importance

What is population data in research?

A population is a fundamental aspect of our existence. Population data is defined as a set of individuals who share a characteristic or set of these. A population is mainly determined by geographies, such as all people in California, or all people in the United States. Demographers (people who study human populations) categorize this as the natural population. A collection of any living beings is considered a population, but we will focus only on human populations in this blog.

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Geography is one of the many ways in which the population is defined and analyzed. The era, political inclinations, religious beliefs, or physical characteristics are ways of dividing people into different communities. The study of populations is achieved by examining these diverse populations and observing where they coincide. For example, suppose you know the population of Americans who are Republicans and see the population that lives in Texas. In that case, you can study where those populations are intertwined and learn something about Republicans and Texans.

Why is accurate population data necessary?

Critical decisions for a nation, organization, or family are made based on population data. Population data contains various influential details such as birth, death, demographic information such as age, sex, annual income, occupation, language, etc. The overall socio-economic, economic, political, cultural progress of a country is dependent on population data to a large extent.

Answers to questions such as “How many of us are there in the country?”, “On what basis are we divided?” “Do we possess enough food, land, and other such resources?” are obtained by evaluating population data.

Characteristics of population data

The amount of people in the population is not all that can be known about these. There are also data such as:

Age: The age of a population can tell us a lot about what that population is doing and what it is going to do in the future.

Location: Finding out where people live is one of the main reasons why various countries conduct their census. Many government programs also base their funds on demographic patterns. The location data also inform us about the movement of people.

Socio-economic Data: They help us know the type of concentrations of people in some urban regions or the high concentrations of people with cancer near certain industrial zones.

Race: The demographic study of the breed is very controversial. Scientifically, there are no different “races” of human beings. The difference between Asians and blacks is the same as the difference between people with brown eyes and blue eyes. However, the idea of race continues to play an essential role in our societies. Many of us identify ourselves as part of a certain race for cultural reasons.

Human population data classification and estimation

There are two primary classifications of population data:

• Primary population data collection sources: Data collected directly by a researcher or statistician or a government body via sources such as census, sample survey, etc. are called primary population data collection.
• Secondary Population Data Collection Sources: Data obtained from existing sources such as journals, newspapers, magazines, annual research reports, etc. and not directly by a government or a research organization is called secondary population data collection.

The below-mentioned resources are the most used for human population data classification.

• Census: The simplest, yet not the most accurate or useful way to evaluate population is counting everyone. This is known as a census and is usually done by governments. In the past, religious organizations carried out censuses, but generally at a local or regional level. The Roman Empire carried out censuses to estimate the group of men of military age and for tax purposes, but these were limited since the Romans had to report with the government officials in their hometown to be counted. Poor people or those who could not travel were rarely counted.

A census is sometimes referred to as a complete enumeration. Each person is counted by personal interviews,  surveys, or any other type of interview. There are no estimates.

Even a complete census has limits. In countries with very remote areas, it may be impossible for census takers to count everyone.

There are two ways of conducting census:

• De facto method: When the census is conducted at an individual’s current residence, it is known as the de facto method. Generally, this census is carried out at night, and thus, it is also known as ‘one- night enumeration.’ It is conducted in urban regions in a country with high income.
• De jure method: When the census is conducted at a person’s permanent residence, it is known as the de jure method. Compared to de facto, it is more practical and scientific and is also called ‘period enumeration.’ Nepal is one of the very few countries which follow this method.

Census has a list of the following attributes:

• Geographic segmentation attributes include current residence, permanent residence, place of birth, workplace information, etc.
• Personal and demographic analysis details such as age, sex, marital status, literacy, language spoken at home, the number of people residing at home, etc.
• Information on an individual’s economic background, such as occupation, the current status of employment, primary source of income, etc.
• Sample surveys: An alternative to a full enumeration census is a sampling. You might be familiar with this as the method that market research companies and political analysts use to conduct their research. Statisticians use a mathematical formula to know the minimum number of people needed to constitute a population’s representative sample. For example, if the total population is 1,000 people, researchers could directly survey 150 of them. Then, they can take the data from the sample and extrapolate it to the entire population. If 10% of the sample people are left-handed, it can be assumed that 100 of a population of 1,000 are left-handed.

 Sampling can yield more accurate results than full enumeration, but there are some caveats. All samples have a margin of error because of the possibility that samples differ from the total population.

 This is expressed in terms of variation of error percentage, such as +/- 4%. The larger the sample size, the smaller the margin of error. Besides, samples must be chosen in the most unexpected way possible. This can be more difficult than it sounds.

 Let’s say you want to survey a sample of all people in Chicago. A method used in the past was to select random names from the phone book. However, this eliminates the possibility of certain classes of people being selected for the sample: low-income people who do not have a telephone.  

• Administrative records: The collection of population data from places that do not carry out censuses or historical periods where censuses were not common is achieved by gathering all available demographic information in administrative records. There could be partial censuses, data from the local population, or information collected by religious or civic groups. Examining birth and death records provides other clues.

LEARN MORE: Population vs Sample

Importance of population data

Collecting and analyzing population data is integral as there is constant change in each passing day, month, and year. Here are three main reasons why population data is essential:

• Collect data on population growth and decline:

The human population has increased practically non-stop throughout history. In 1,000 BC, there were between 1 and 10 million human beings. That number rose to 50 million in 1,000 BC. In 600 AD, the world population had reached 200 million, and at the beginning of the 20th century, 1,500 million human beings lived on the planet.

 Our population seems to increase with more incredible speed as the centuries pass. The main reason for this is simple: every increase in population creates more people able to reproduce. The population grows exponentially.

 According to the Malthus Growth Model, if a million individuals have enough children to double the population (considering mortality rates), then the next generation will be twice in number than what we are today. Doubling people gives rise to four million people.

• Understand the problems that arise due to population increase:

As the population grows, it is put under pressure. This pressure may come from a lack of resources to feed, house, and provide services, an illness; a war; or lack of space. The pressure can be relieved with migration. Wars, diseases, and famine also relieve workplace stress as they kill part of the population.

Malthus’s theory is known as” The Population Explosion” (The Population Bomb), and gained popularity with the environmental movement in the 70s fears of global overpopulation are based on several factors:

• We will not be able to produce enough food to feed everyone.
• There is not enough space for everyone to live in.
• Humans harm the environment. Too many humans will practically destroy the ecosystem, further reducing our ability to produce food.
• We can not provide the social infrastructure to care for all people.

Our vulnerability to these factors is based on population density; the number of people per unit area. Since the Industrial Revolution, urbanization has caused a massive increase in population density in cities.

 The highest population density may have occurred in the walled city of Kowloon in Hong Kong. About 50,000 people lived in a mega block that averages about 150 by 200 meters. The practically anarchic district was evacuated and demolished to build a park. Nowadays, the areas of the most significant demographic density are found in the main urban areas. India and China have large areas of high population density.

 As population density increases in a given area, it approaches what is known as carrying capacity. This is the maximum number of people an area can support in terms of available resources.

 For animals, this is easy to calculate. For example, a goat might need 50 square yards of grass to survive. Therefore, an area of 200 yards can load four goats. Estimating the carrying capacity for humans is much more complicated. We can use technology to optimize our production of resources. We can transport resources from other areas. We can create sanitation systems and other infrastructures to support a higher density.

Control of the population

What happens when we reach the load capacity in an area? There are several options:

• People move to another area.
• People are less healthy, therefore, less able to reproduce.
• The pressure of the population leads to war.
• Unsanitary conditions and proximity cause outbreaks of disease.
• We optimize the generation of resources and infrastructure, increasing the load capacity.
• Humans are also able to control their populations voluntarily. This can occur on a large scale, such as a program or government law or individual level. People have had greater access to birth control since the 1960s.

Governments, for example, the Chinese government, controlled the increase in population by imposing penalties for having too many children. This way, having fewer children seems more convenient, which leads to more people sterilizing themselves. Unfortunately, some governments have adopted genocide, i.e., have tried to reduce or eliminate specific populations that they consider undesirable by killing them in masses.