1.3 Quota and opportunity sampling Flashcards
Quota sampling method
- Population divided into groups according to characteristics, with a quota of items/people in each group set to try and reflect the group’s proportion in the whole proportion.
- Quotas are calculated in the same way as stratified sampling.
- Randomly select sampling units until quotas are reached.
- Once a quota is full, any subsequent sampling units should be released.
Advantages of quota sampling
Relatively quick, easy and inexpensive
No sampling frame required
Allows a small sample to still be representative of the population
Disadvantages of quota sampling
Non-random sampling can introduce bias.
Population must be divided into groups, which can be costly or inaccurate
Can depend on knowledge/expertise of researcher
Opportunity/Convenience Sampling
Sample taken from first n people who are available at time of study, who meet criteria
Advantages of opportunity/convenience sampling
Easy to carry out
Inexpensive
Disadvantages of opportunity/convenience sampling
Unlikely to provide a representative sample
Highly dependent on individual researcher
Qualitative/categorical data
Non-numerical values e.g. colour
Types of quantitative data
Discrete
Continuous
Discrete data
Can only take specific values e.g. shoe size, number of children
Continuous data
Can take any decimal value e.g. height, weight
What is use of the midpoint?
Use of the midpoint assumes values are evenly distributed throughout the interval
How to improve research methods
Larger sample
Vary time, day and location of research
Opportunity sampling method
- Divide the sample into the same proportion as the population to create each quota, assign each person the researcher meets to a quota, then continue to ask/observe people until each quota is full
