Random Sampling:
Random sampling is a technique where each item in the population has an even chance and likelihood of being selected in the sample. Here the selection of items completely depends on chance or by probability and therefore the name ‘method of chances’.The main attribute being every sample has the same probability of being chosen.
The steps involved in simple random sampling:
A list of all the members of the population is prepared initially and then each member is numbered starting from 1.
From this population, random samples are chosen in two ways:
Random number tables
Random number generator software (preferred more as the sample numbers can be generated randomly without human interference)
To minimize any biases in the process of simple random sampling, there are two approaches:
Method of lottery:
One of the oldest methods which is a mechanical example of random sampling. Here, each member of the population is numbered systematically. By writing each number on a separate piece of paper, they are mixed in a box and then numbers are drawn out of the box in a random manner.
Use of random numbers:
The use of random numbers(table) is an alternative method that also involves numbering the population.
Advantages of random sampling:
No restriction on the sample size even when the population size is large.
The quality of the data collected through this sampling method depends on the size of sample i.e., more the samples better the quality of the data.
Disadvantages of random sampling:
Costly method of sampling as it needsthe complete list of all potential data to be available beforehand.
Not suitable for face-to-face interviews in larger geographical areas due to cost and time constraints.
The larger population means a larger sample frame which is difficult to manage.
In Excel we have the function:
RAND() which generates a random number X where 0 ≤ X <1
RAND()*100 which generates a random number X where 0 ≤ X <100
INT(RAND()*100) which generates a integer random number X where 0 ≤ X <100
When we click on drag, we can have the function for the selected cells as shown
