Sampling Techniques Flashcards
What is sampling?
How the researcher gets the sample to include within the research, aiming to obtain a sample that represents a target population
What is a target population?
A group of people that the researcher is interest in, from whom a sample is drawn and about whom a generalisations can be made
What is random sampling?
A sample produced by using a random techniques so every member of the target population has an equal chance of being tested
What are the two ways random sampling can be done?
- Lottery method: all names in a lottery hat and select the number of names required
- Random number generator: assign each person a number. Using the generator, participants are selected until you have the desired sample
What are advantages of random sampling?
- There’s little research input and each person has an equal chance of being selected so it isn’t affected by researcher bias
- It’s quicker to conduct than other techniques
What are disadvantages of random sampling?
- There’s chance that the sample obtained doesn’t represent the target population
- It requires a full list of the target population
What is systematic sampling?
- Uses a predetermined system to select participants e.g. every nth person
- Requires an alphabetically ordered list of individuals and a random generator to get the nth term. Then select every nth term person until sample is complete
What is an advantage of systematic sampling?
Little research bias as participants are selected using an objective system and each person has an equal chance of being selected
What are disadvantages of systematic sampling?
- May not be always representative as the sample is left to chance
- It takes time and resources to do as it requires a full list of the target population to be obtained and ordered
What is stratified sampling?
- The subgroups (strata) within a population are identified, who have a key characteristic which should be present in the final sample
- Participants are then obtained from each strata in proportion to their occurrence in the population
- Selection from the strata is random
What are advantages of stratified sampling?
- It produces the most representative sample as it’s designed to accurately reflect the composition so generalisations of the findings are possible
- There’s little researcher bias as it still uses randomisaton
What is a disadvantages of stratified sampling?
It may be impractical as it requires a full list of the population to be obtained and it here must be ensured that a key characteristic present in the population is selected across the strata, so it’s time-consuming
What is opportunity sampling?
Recruiting participants who are both easily accessible and willing to take part
What is an advantage of opportunity sampling?
One of the easiest and quickest methods as it uses the first suitable participants that you can find
What are disadvantages of opportunity sampling?
- Researchers have control over where they look for participants. They may pick a location or group of people they ‘like the look of’, which may result in confirmation bias, where the researcher uses participants that will confirm their beliefs
- Participants are selected bases on convenience and so doesn’t reflect target population
What is volunteer sampling?
Participants self-select to be part of the study, usually responding to an advert of the study
What is an advantage of volunteer sampling?
There’s little researcher bias as those selected are due to chance
What are disadvantages of volunteer sampling?
- The sample may be unrepresentative as participants are likely to be those with extra time on their hands or might be more motivated by the money offered than others, resulting in volunteer bias
- Although it’s quicker to conduct than other methods, a full list of the target population is required
