Types Of Sampling Flashcards
What is Simple random sampling and how do you carry it out
When every sample has an equal chance of being selected.
Each item has its own identifying number in the sampling frame.
Use a random number generator or lottery sampling (use Calculator function).
What is Systematic sampling And how do you carry it out
When required elements are chosen at regular intervals from an ordered list.
K = population size/ sample size.
Take every kth element starting between one and k.
What is stratified sampling and how do you carry it out?
Where the population is divided into groups (strata) and a simple random sample is carried out in each group. Each strata is proportional to the population size. it is used when the sample is large and the population naturally divides into groups.
What is quota sampling and how do you carry it out?
The population is divided according to a characteristic. A quota of items or people in each group is set to try and reflect the groups proportion in the whole population. The interviewer selects the actual sampling units.
What is opportunity sampling?
When a sample is taken from people who are available at the time of study who met Certain criteria
Name all the types of random sampling
Simple random, systematic, stratified.
Name all the types of nonrandom sampling
Quota sampling, opportunity sampling
What are the advantages to Simple random sampling?
There is no bias, easy and cheap to implement, Each number has a known and equal chance of being selected
What are the disadvantages to simple random sampling?
It is not suitable when the population size is large and a sampling frame is needed
What are the advantages to systematic sampling?
It is simple and quick and suitable for large populations
What are the disadvantages to systematic sampling
A sampling frame is needed and if this sampling frame is not random can introduce bias
What are the advantages to stratified sampling?
It reflects the population structure and guarantees proportional representation of groups within the population.
What are the disadvantages to stratified sampling?
The population must be clearly classified into distinct strata and selection within each stratum suffers from the same disadvantages as random sampling
What are the advantages to quota sampling?
It allows a small sample to still be representative of the population. No sampling frame is required and it is quick easy and inexpensive. Comparison between different groups and populations is easy
What are the disadvantages to quota sampling?
Nonrandom sampling can introduce bias. The population must be divided into groups which can be costly/inaccurate. Increasing the scope of a study increases number of groups adding time/expense. non-responses are not recorded.
