Simple and Stratified Random Sampling:
Simple Random Sampling is a type of probability sampling that ensure that each element of the population has an equal and independent chance of being chosen. The first step is to identify the accessible population and enumerate or list all the elements of the population. This listing is called sampling frame. After sampling frame is developed, a method must be selected to choose the sample. Table of random number includes a list of numbers that have been generated in such a way that there is no order or sequencing of the number. Today these tables are generated through the use of computers:
Stratified Random Sampling: Ther'e are many different characteristics that may call for the use of stratified sampling. It is a type of random sampling in which the population is first divided into two or more strata or subgroups, before sampling process begins. Each unit is assigned to one stratum based on prior knowledge about the unit. Then, independent random samples are selected from each stratum using a procedure which is used in simple random sampling. Stratum (plural "siratan) constitutes a portion of the population i.e. they are mutually exclusive and collectively exhaustive. The sampling units of stratum are similar in each other and the different from the members of another stratum in the characteristics that we are measuring.