What is A Population?

Population V/s Sample

Population is the collection of all the objects, individuals or events that need to be studied. It is usually bigger in number.

Example — If we need to find the height of every person living in a country say X. All the people or subjects will collectively be called a population.

Since practically it is impossible to measure everyone in the country what we can do, we can randomly select some people from different places within the country and measure their heights. This smaller group is called a sample

A sample is a subset of the population. There are different ways to create a sample but it is always ensured that a sample must try to maintain the heterogeneity of the population.

This is where inferential statistics come into play. We make our study (viz. measuring height) for the sample and Generate a hypothesis (also called an assumption) then apply it to the whole population.

Example — If the mean (average) height of our sample is 170 cm then we can say that the mean (average) height of the population will be around 170cm.

Number of subjects in population >> Number of subjects in sample

Some Terminologies to keep in mind:

1. Population Mean (μ) — It is the mean of any attribute (like the height of people) calculated for the whole population.
2. Sample Mean (x̄) — It is the mean of any attribute calculated only for the sample.
3. Heterogenous Population/Sample — A collection where all the subjects are different or have different choices.
4. Homogenous Population/Sample — A collection where all the subjects have the same choice.