Sampling Flashcards
Define census
Something that measures every member of a population
What are the positives of using a census?
It gives an accurate result
What are the negatives of using a census?
It can be expensive
The testing may destroy the samples
What are sampling units?
The individuals of a population
What is the sampling frame?
The list of sampling units
What are the 3 types of random sampling?
- Simple random sampling
- Systematic sampling
- Stratified sampling
What is simple random sampling and how do we do it?
Where every sampling unit has the same chance of being selected. Sample using lottery sampling or random number generator
What is the advantages and disadvantages of simple random sampling?
+ bias free
- need sampling frame
How do we do systematic sampling?
Pick a random number between 1 and k (population/sample) and take every kth unit
What is the advantages and disadvantages of systematic sampling?
+ quick to use
-need sampling frame
How do we do stratified sampling?
- Divide sample into groups (strata)
- Sample/ population x strata for each strata to find proportion of samples you need
- Pick randomly from each group to fill your sample
What is the advantages and disadvantages of stratified sampling?
+ reflects the population
- population must be classified in strata
What are the 2 types of non-random sampling?
Quota sampling
Opportunity sampling
What is quota sampling?
When the population is split into groups but are filled using opportunity sampling
What is the advantages and disadvantages of quota sampling?
+ no sampling frame needed
- potential bias
What is opportunity sampling?
When the quota is filled by those available at the time
What is the advantages and disadvantages of opportunity sampling?
+ easy/cheap
- unlikely to be representative, bias
