1.3 Non-random sampling Flashcards
What are the two types of non-random sampling?
-Quota
-Oppurutunity
Describe quota sampling
In quota sampling, an interviewer, or researcher selects a sample that reflects the characteristics of the whole population
Describe opportunity sampling
Opportunity sampling consists of taking the sample from people who are available at the same time the study is carried out and who fit the criteria you are looking for.
Explain in detail the process of quota sampling
The population is divided into groups according to a given characteristic. The size of each group determines the proportion of the sample that should have that characteristic.
As an interviewer, you would meet people, assess their group and then, after the interview, allocate into the appropriate quota.
This continues until all of the quotas have been filled. If a person refuses to be interviewed or the quota into which they fit is full, then you simply ignore them and move onto the next person.
Explain the process of Opportunity sampling
This could be the first 20 people you meet outside a supermarket on a Monday morning who are carrying shopping bags, for example.
What are the advantages of quota sampling?
- Allows a small sample to still be representative of the population
- No sampling frame required
- Quick, easy and inexpensive
- Allows for easy comparison between different groups within a population
Disadvantages of quota sampling
- Non-random sampling can introduce bias
- Population must be divided into groups
- Increasing scope of study increase number of groups
- Non-responses are not recorded as such
What are the advantages of oppurtunity sampling?
- Easy to carry out
- Inexpensive
What are the disadvantages of opportunity sampling?
- Unlikely to provide a representative sample
- Highly dependant on individual researcher
