Population

Population:

The concept of population and sample are to be understood clearly as they have significance role in the context of statistics.

The word population or statistical population is used for aggregate of all units or objects within the purview of enquiry. We may be interested in the level of education in a college of Tamil Nadu. Then all the students in the college will make up the population. If the study is aimed to know the economic background of Hr. Secondary students of a school, then all the students studying +1 and +2 classes of that school is the population. The population may contain living or non-living things. All the flowers in a garden or all the patients in a hospital are examples of populations in different studies.

Finite Population

A population is called finite if it is possible to count or label its individuals. It may also be called a Countable Population. The number of vehicles passing in a highway during an hour, the number of births per month in a locality and the number of telephone calls made during a specific period of time are examples of finite populations. The number of units in a finite population is denoted by N and is called the size of the population.

Infinite Population

Sometimes it is not possible to count or label the units contained in the population. Such a population is called infinite or uncountable. The number of germs in the body of a sick patient is uncountable.

Sampling from a finite population will be considered in the rest of the chapter. Sampling from an infinite population can be handled by considering the distribution of the population. A random sample from an infinite population is considered as a random sample from a probability distribution. This idea will be used when we study testing of significance in the second year.