Concept of Universe or Population and Sample

 

What is Universe or Population
the term ‘Universe’ refers to the total of the items or units in any field of inquiry.whereas the term ‘Population’ refers to the total of items about which information is desired. Example: Universe  : All the Teachers Population  : All primary teachers, all college teachers, all university students etc.Population Size: The total number of units present in the population
Types of Population
Based upon Countable manner-Finite Population -Infinite Population
Based upon Researcher reasonable access-Accessible population -Target population
Based upon Existence of the population-Real population-Hypothetical Population
Finite Population: 
If the population consists of fixed and limited number of items or units, it is known as finite population.Example:  the workers in a factory, students in a college etc. The symbol ‘N’ is generally used to indicate how many elements (or items) are there in case of a finite population
Infinite Population: An infinite population is that population in which it is theoretically impossible to observe all the elements. in an infinite population the number of items is infinite i.e., we cannot have any idea about the total number of items.Example: The number of stars in a sky, possible rolls of a pair of dice are examples of infinite population

Target population (universe) The entire group of people or objects to which the researcher wishes to generalize the study findingsExample: All people with AIDS
Accessible population It is a subset of the target population where researcher try to classify with his or her reasonable access.Examples: All people with AIDS in the Bengal area.
Real population: Population consisting of the items which are all present physically is termed as real population. Example: no of court case in a day, no of snake bite patients admitted in the hospital etc.
Hypothetical Population: Population consisting of the results of repeated trials is named as hypothetical population. Example: The tossing of coin, rolling of a dice etc,

What is a Sample ? A smaller representation of the population /large /whole group.A sample is a smaller, manageable version of a larger group. It is a subset containing the characteristics of a larger population.Samples are used in statistical testing when population sizes are too large for the test to include all possible members or observations. A sample should represent the whole population and not reflect bias toward a specific attribute. Sample Size (n): the total number of units in the sample

Types of Sample
Small Size Sample or Small Group Sample :Less then 30 samples
Large Size Sample or Large Group Sample More then 30 samples