upon the nature of the data and the type of enquiry. The procedures of selecting a sample may be broadly classified as . Non-Random sampling or Non- probability sampling. .
Random Sampling or Probability sampling. Here we confine ourselves to Random sampling or Probability sampling. Note Random sampling or Probability sampling Random sampling refers to selection of samples from the population in a random manner. A random sample is one where each and every item in the population has an equal chance of being selected.
“ Every member of a parent population has had equal chances of being included”.- Dr. Yates “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 The following are different types of probability sampling: (i) Simple random sampling (ii) Stratified random sampling (iii) Systematic sampling (i) Simple random sampling 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. Simple random sampling may be done, with or without replacement of the samples selected. In a simple random sampling with replacement there is XII Std - Business Maths & Stat EM Chapter - - Sampling Techniques and Statistical Inference sample can be done through “Random Number Table”.
The random number table has been so constructed that each of the digits , , ,…, will appear approximately with the same frequency and independently of each other. The various random number tables available are a. L.H.C. Tippett random number series b.
Fisher and Yates random number series c. Kendall and Smith random number series d. Rand Corporation random number series. Tippett’s table of random numbers is most popularly used in practice.
Given below the first forty sets from Tippett’s table as an illustration of the general appearance of random numbers: