Studied by 1 person
What is the definition of a census
A census collects data about all the members of a population
What is the main advantage of a census
Gives fully accurate results
What are the disadvantages of a census
time consuming
Expensive
What are the advantages of sampling
Quicker and cheaper than census
Less data needs to be analysed
What are the disadvantage of sampling
Might not represent the population accurately
Can introduce bias
What are the 5 types of sampling
Simple random, systematic, stratified, quota and opportunity (convince)
What is the definition of random sampling
Every member of a group has an equal chance of being selected
What is the definition of Biased sampling
A sampling method from which misleading conclusions about the population could be drawn
What is the definition of Simple random sampling
Every possible sample of size n has an equal chance of being selected as the sample
Describe the method for simple random sampling
uniquely number every member of a population
Randomly select n different numbers using a random number generator
What are the pros of simple random sampling
unbiased
Quick for a small population when you want a small sample
What are the cons of simple random sampling
time consuming for large population
Can’t be used if not possible to number all members
What is the definition of Systematic sampling
A sample is formed by choosing members of a population at regular intervals using a list
What is the method for systematic sampling
Calculate the size of the interval ‘k’
Choose a random starting point between 1 and ‘k’
Select every kth member after the first one
What’s the equation for calculating the size of the interval for systematic sampling
Size of population (N) / size of sample (n)
What are the pros of systematic sampling
Useful when there is a natural order
Quick and easy for large populations and samples
What are the cons of systematic sampling
List needs to be in a random order to avoid bias
A sampling frame is needed
What is the definition of stratified sampling
The population is divided into specific groups and a random sample is taken from each
What is the method for stratified sampling
Calculate the number of members sampled from each group
Take a random sample from each group
What are the pros of stratified sampling
useful when different groups in a population
Sample will be representative of the population structure
Members are chosen randomly
What are the cons of stratified sampling
Can’t be used if it is not possible to split the population into groups
Time consuming for large population
Can’t be used if you can’t number all members
