Stats

Created by

Bobby Branson

Cards (17)

What is a simple random sample? 
Where every sample of size n has an equal chance of being selected.
What is systematic sampling? 
Where the required elements are chosen at regular intervals from an ordered list.
What is stratified sampling? 
Where the population is divided into mutually exclusive strata and a random sample is taken from each.
Advantages of simple random sampling. (3) 
Free of bias
Easy and cheap for small populations and samples
Each sampling unit has a known and equal chance of selection
Disadvantages of simple random sampling. (2) 
Samping frame is needed
Not suitable when population is large
Advantages of systematic sampling (2) 
Simple and quick to use
Suitable for large samples/populations
Disadvantages of systematic sampling (2) 
A sampling frame is needed
Can introduce bias if sampling frame is not random
Advantages of stratified sampling (2) 
Sampling accurately reflects population structure
Guarantees proportional representation of group within a pop.
Disadvantages of stratified sampling (2) 
Population must be clearly classified into distinct strata
Sampling frame need for each strata
Unsuitable for large pop in each strata
What is quota sampling? 
A sample is collected that reflects the characteristics of the whole population.
What is opportunity sampling? 
Where the sample taken is from people who are available at the time of the study and who fit the criteria you are looking for.
Advantages of quota sampling (2) 
No sampling frame needed
Quick easy and inexpensive
Disadvantages of quota sampling (2) 
Population must be divided into group, costly
Non random sampling can introduce bias
Disadvantages of opportunity sampling (2) 
Dependent on researcher
Unlikely to be representative
Advantages of opportunity sampling (2) 
Easy to carry out
Inexpensive
What is a sampling frame? 
List of individual sampling units.
What is a sampling unit? 
One individual observation set from the population.