Data collection Flashcards
What is simple random sampling?
Items in the sample are chosen by a random number generator or drawing tickets out of a box. Every possible sample has the same probability of being selected. Every member of the population has an equal chance of being selected. Every member of the population is listed.
What is cluster sampling?
Population is divided into subgroups which are representative of the entire population. Taking a sample from a few of these subgroups.
For example taking a sample of students might take a sample from 2 or 3 different schools.
What is Quota sampling?
A quota sample similar to stratified but it is specific to the number of data items required. A number if females and a number of males might be required.
What is Self selected sampling?
In self selected sampling, individuals in the sample have chosen to be in the sample like responding to a survey/
What is systematic sampling sampling?
A method of choosing individuals to form a sample. Like obtaining an alphabetical list in a year group and choosing every 10nth member. Chosen at regular intervals in a list.
The person should be chosen by doing the population size/ sample size.
What is Stratified sampling?
Populations divided into groups and a simple random sample is carried out in each group.
Same proportion = Sample size / Population size
Used when sample is large
What is Opportunity/ Convenience sampling?
Sample is taken from people who are available at time of the study who meet the criteria.
What are the advantages and disadvantages of simple random sampling?
Advantages: Bias free, Easy and cheap to implement. Each number has a known equal chance of being selected
Disadvantages: Not suitable when the population size is large. Sampling frame is needed.
What are the advantages and disadvantages of systematic sampling?
Advantages: Simple and quick to use. Suitable for large sample populations.
Disadvantages: Sampling frame is needed . Can introduce bias if sampling frame is not random.
What are the advantages and disadvantages of Stratified sampling?
Advantages: Reflects population structure. Guarantees proportional representation of groups within population
Disadvantages: Population must be clearly classified into distinct groups.
Selection within each groups has the same disadvantage as random sampling.
What are the advantages and disadvantages of Quota sampling?
Advantages: Allows small sample to still be representative of population. No sampling frame is required.
Quick and easy inexpensive. Allows for easy comparison between different groups in population.
Disadvantages: Non random sampling can introduce bias. Population must be divided into groups which can be costly and inaccurate. Long time. Non responses are not recorded.
What are the advantages and disadvantages of Opportunity sampling?
Advantages: Easy to carry out and inexpensive.
Disadvantages: Unlikely to provide representative sample. Highly dependant on individual researcher.
