Sampling is process of getting the samples that are small fractions of attributes from the universe in order to get some sort of inference about the whole universe. At times it is very difficult to survey the whole universe. That’s why the concept of sampling comes into picture. The theory of statistical inference requires the existence of sampling procedure in order to have a fair idea about the conclusion. Broadly the sampling is categorized as random and non-random sampling. Let’s have a look into the different kinds of sampling techniques.Sampling is a term which describes the process of converting a signal into the numeric sequence. Though the theory of sampling has been developed only during the last few decades the idea of sampling is not new. People have been using sampling theory without knowing about it. Normally people examine and inspect a small sample from a universe and take a decision about accepting or rejecting the items of the whole lot from which the sample has been taken. For example, a grain merchant does not examine each grain of wheat that he purchases. He simply takes out a handful and from it gets an idea about the quality of the whole consignment.

To understand sampling, you need to first understand a few basic definitions.

• The total set of observations that can be made is called the population.
• A sample is a set of observations drawn from a population.
• A parameter is a measurable characteristic of a population, such as a mean or standard deviation.
• A statistic is a measurable characteristic of a sample, such as a mean or standard deviation.
• A sampling method is a procedure for selecting sample elements from a population.
• A random number is a number determined totally by chance, with no predictable relationship to any other number.
• A random number table is a list of numbers, composed of the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. Numbers in the list are arranged so that each digit has no predictable relationship to the digits that preceded it or to the digits that followed it. In short, the digits are arranged randomly. The numbers in a random number table are random numbers.