Census and Sample : Under the census data are collected for each and every unit of population on the other side sampling is simply the process of learning about the population on the basis of a sample The sampling can be grouped under two broad heads probability sample and non probability sample . where as probability sampling method are those in which every item in the universe has probability of being chosen for the sample. where as non-probability sampling method are those which do not provide every item in the universe with a known chance of being included in the sample. 1. Probability Sampling Method (a) Sample Random Sampling : Lottery Method, Table of Random Number (b) Systematic Sampling: In it the first sample is selected randomely and generally followed by Kth students K=N/n K= Sampling Interval , N= Universe Size and n= Sample Size for example in a class 100 students with roll no from 1 to 100. It is decided to take a sample of 10 students. Use systematic sa