# Concept of Sampling || Estimation and Hypothesis Testing

## Concept of Sampling

### Population

A population is the totality of items understudy during sampling. The size of the population is denoted by ‘N’. There are two types of population i.e. finite population and infinite population. A population having a finite number of items that is possible to enumerate is called a finite population and a population having an infinite number of items that are impossible to enumerate called an infinite population.

### Sample

A sample is a small portion of the population that is drawn from the population by using the sampling technique. The main objective of the sample is to estimate population parameters. The size of the sample is denoted by ‘n’.

### Parameter

Population characteristics or summary measures of the population are called parameters and they are always constant. Parameters are calculated from the population data or they are estimated from the sample statistics.

### Statistics

Sample characteristics or summary measures of the sample are called statistics and they varied from sample to sample. Statistics are used to estimate the corresponding population parameters. The size of the sample is denoted by ‘n’.

### Sampling Frame

A sampling frame is a set of sampling elements with identification particulars or a map showing the positions of the sampling elements. A sampling frame represents the population under investigation.

### Census Survey

Every unit of the population will be studied and the study and results are based on all units of the population.

### Sample Survey

A representative number of small sample units will be studied and information obtained through these selected units will be used to estimate the population parameters to make the decision about the entire population.

### Sampling

The process of selecting the representative sample units from the population to study the characteristics of the population is called sampling. In many empirical studies., data are to be collected from a population under study. A population consists of the number of units usually very large and sometimes infinitely large. In many cases, it is not practically possible to include all units of the population for the investigation. Therefore, a few units of the population have to be selected as a representative of the whole population. So, sampling is needed in this situation to draw a representative sample of the population.

### Objective of Sampling

• To obtain maximum information about the population under consideration by examining the number picked up in the sample.
• To ascertain the confidence interval to the estimate of the population parameter.
• To test the significance of the population parameter at a given level of significance.

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