Paper 3 data Flashcards
Why do we sample data?
To save time, energy, money, labour/ man power, equipment, access to suitable sites to ensure every single item or site within the parent population or whole sampling frame.
What are the three types of sampling techniques?
Random Sampling
Systematic Sampling
Stratified Sampling
What is Random Sampling?
Selecting a data collection site at random
Give an advantage of Random Sampling:
Every person/ site has equal chance of being included = representative
Give a disadvantage of Random Sampling:
Can cause bias because you can be drawn to certain groups which affects reliability of results
What is Systematic Sampling?
Collecting data in an ordered or regular way
Give an advantage of systematic sampling:
Allows a good coverage of the study area.
More straightforward
Give a disadvantage of systematic sampling:
Can miss certain groups/ sites altogether due to every nth person/ metres which could skew results
What is Stratified Sampling?
Dividing sampling into groups
Give an advantage of stratified sampling:
Selects groups which means data is more representative of the whole population
Give a disadvantage of stratified sampling:
Need to access background information to avoid over/ under representation of groups
Give an example of random sampling:
Random person to interview
Random site on a river
Give an example of systematic sampling:
Stopping every 10th person
Taking measurements every 20 metres along a river
Give an example of stratified sampling:
Samples from each course of a river
5 people from each age/ socioeconomic group
Give an advantage of a choropleth map:
Easy to construct
Shows a visual impact for the data