Select the required number of samples from any row or column or diagonal. Select at random, any page from the ‘Random Number Table’.ģ. Identify the N units in the population with the numbers from 1 to N.Ģ. The procedure of selecting the random samples consists of following steps:ġ. Similarly if N(< 999) or (< 9999), then any three digit random number or four digit random number can be selected from (000 to 999) or (0000 to 9999). Suppose, if we want to select the required number of samples from a population of size N(<99) then any two digit random number can be selected from ( 00 to 99) from the above random number table. Given below the first forty sets from Tippett’s table as an illustration of the general appearance of random numbers: Tippett’s table of random numbers is most popularly used in practice. The various random number tables available areĬ. The random number table has been so constructed that each of the digits 0,1,2,…,9 will appear approximately with the same frequency and independently of each other. The most practical, easy and inexpensive method of selecting a random sample can be done through “Random Number Table”. The alternative method is that of using the table of random numbers. When the population size is large, it is difficult to number all the items on separate slips of paper of same size, shape and colour. If the population or universe is infinite, this method is inapplicable. This method is mostly used in lottery draws. This method is called unrestricted random sampling, because units are selected from the population without any restriction. The selection of items thus depends on chance.įor example, if we want to select 10 students, out of 100 students, then we must write the names/roll number of all the 100 students on slips of the same size and mix them, then we make a blindfold selection of 10 students. Then the required numbers of slips are selected for the desired sample size. They are folded and placed in a container and shuffled thoroughly. In this method, all the items of the population are numbered on separate slips of paper of same size, shape and colour. This is the most popular and simplest method when the population is finite. Of those, the following two methods are generally used and which are described below. Several methods have been adopted for random selection of the samples from the population. Thus in simple random sampling from a population of N units, the probability of drawing any unit at the first draw is 1/N, the probability of drawing any unit in the second draw from among the available (N-1) units is 1/(N-1). So, simple random sampling without replacement is followed. In a simple random sampling with replacement there is a possibility of selecting the same sample any number of times. Simple random sampling may be done, with or without replacement of the samples selected. In this technique the samples are selected in such a way that each and every unit in the population has an equal and independent chance of being selected as a sample. The following are different types of probability sampling: “A random sample is a sample selected in such a way that every item in the population has an equal chance of being included”.-Harper “ Every member of a parent population has had equal chances of being included”.- Dr. A random sample is one where each and every item in the population has an equal chance of being selected. Random sampling refers to selection of samples from the population in a random manner.
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