Sampling Methods Flashcards
What are the methods of random sampling?
Simple, systematic, stratified
What are the methods of non-random sampling?
Quota, Opportunity
What is a sample?
a selection of observations taken from a subset of the population which is used to find out information of the population as a whole
What is a census?
observes or measures every member of a population
What are the advantages of a census?
it should give a completely accurate result
What are the disadvantages of a census?
time consuming and expensive
hard to process large quantity of data
What are the advantages of a sample?
less time consuming and expensive than a census
fewer people have to respond
less data to process than in a census
What are the disadvantages of a sample?
data may not be as accurate
sample may not be large enough
What is a simple sample?
sample of size n where every sample of size n has an equal chance of being selected
What is a systematic sample?
the required elements are chosen at regular intervals from an ordered list
What is a stratified sample?
the population is divided into mutually exclusive strata (e.g males and females) and a random sample is taken from each
What is a quota sample?
an interviewer or researcher selects a sample that reflects the characteristics of the whole population
What is an opportunity sample?
taking the sample from the people who are available at the time the study is carried out and who fit the criteria you are looking for
What are the advantages of simple random sampling?
unbiased
each member of the population has the same chance of being chosen
easy and cheap to implement for small populations
data from a random sample can be used in statistical calculations
What are the disadvantages of simple random sampling?
a sampling frame is needed
the sample may not be representative of all sections of the population
