Sampling 🗳️ Flashcards
What is sampling?
Sampling involves selecting participants from a target population.
— The target population is the particular subgroup to be studied, and to which the research findings will be generalised.
— A target population is usually too large to study in its entirety, so sampling techniques are used to choose a representative sample in order to gain credibility.
What are the five common types of sampling?
1) Random
2) Systematic
3) Stratified
4) Opportunity
5) Volunteer
What is random sampling?
With random sampling, every member of the target population has an equal chance of being selected.
+ This involves identifying everyone in the target population and then selecting the number of participants you need in a way which gives everyone an equal chances of being selected, such as pulling names from a hat, or using a computer software package which generates names/numbers randomly without bias.
EVALUATION : Random Sampling
STRENGTH - NO RESEARCHER BIAS
P: A strength of obtaining random sampling is that it is free from researcher bias.
E: Since the sample is generated by a computer generator or selecting names from a hat, the researcher does not have any input into who is selected.
E: This significantly reduces the possibility of them choosing a biased sample of participants who would serve to support their aims.
L: This means that the sample is likely to be representative and so can be generalised to the target population.
LIMITATION - DIFFICULT AND TIME CONSUMING
P: A drawback associated with the random sampling procedure is that it is difficult and time-consuming.
E: It is possible that the people picked may be unwilling to take part in the research.
L: Therefore, this results to the sample being more akin to volunteer sampling.
What is systematic sampling?
Systematic sampling uses a predetermined system used to select its participants.
— For example, every 5th person is chosen and the same interval is then consistently applied to the whole of the target population.
EVALUATION : Systematic Sampling
STRENGTH - NO RESEARCHER BIAS
P: A strength of using systematic sampling is that it is free from researcher bias.
E: Since the researcher is not selecting participants by choice, but by following a predetermined system; this reduces the potential influence that the investigator may have over obtaining the sample.
LIMITATION - POTENTIALLY LACKS REPRESENTATIVENESS
P: A limitation of the systematic sampling method is that it may not be truly unbiased.
E: It might be that every Nth person has a particular characteristic in common, for example being right handed. Although it would be fairly unlikely and unlucky to get a sample who were all similar on a particular trait, it remains a possibility with using the technique.
L: Therefore, the sample generated may not be representative, meaning generalisation to the target population would be more difficult.
What is stratified sampling?
In stratified sampling, subgroups within a population are identified. Participants are obtained from each stratum (‘layer’ or category) in proportion to their occurrence within the population.
— Eg. class with 20 students 18 males and 2 females, the researcher would choose 9 males and 1 female to represent this population proportionally.
EVALUATION : Stratified Sampling
STRENGTH - FREE FROM RESEARCHER BIAS + REPRESENTATIVE
P: A strength of obtaining a stratified sample is that it is largely free from researcher bias.
E: In this technique, the sample is generated randomly once the subcategories/ strata have been identified.
E: This significant reduces the possibility of the researcher choosing a biased sample of participants who would serve to support their aim.
E: This means that sample is likely to be representative because each particular subgroup, if selected appropriately, will be represented within the sample.
L: This means that any findings generated from research with a stratified sample can be generalised to the target population with greater confidence.
LIMITATION - DIFFICULT + TIME CONSUMING
P: There are limitations associated with the stratified sampling method. Ensuing that the subgroups/strata in the target population are all accurately identified is sometimes a difficult and time-consuming task.
E: Furthermore, stratification is not a perfect process since the subgroup identified cannot possibly reflect all the individual differences that exist between those in the target population.
L: Therefore, a truly representative sample would be extremely difficult to obtain using this technique.
What is opportunity sampling?
Opportunity sampling consists of selecting anyone who is available and willing to take part in the study at the time. This technique which is often used in psychological research due to its each of application.
EVALUATION : Opportunity Sampling
STRENGTH - CONVENIENT
P: A strength of opportunity sampling is that it’s a convenient technique.
E: In comparison to all other sampling methods, obtaining an opportunity sample is quicker and easier since it requires less effort on behalf of the researcher.
L: As a result, it is likely to save money and is therefore favoured as the most economical technique.
LIMITATION - BIAS
P: A drawback of opportunity sampling that there is issues with bias as the sample is drawn from a very specific area or location eg. university.
E: This means that it is likely only students will be available to take part who are not representative of the target population.
E: In addition, there is an increased risk of investigator bias as the researcher has complete control over who they approach.
L: This means that they select particular individuals or avoid others according to their own subjective preferences.
What is volunteer sampling?
Volunteer sampling consists of participants self-selecting to take part in a study by either volunteering when asked or by responding to an advert.
EVALUATION : Volunteer Sampling
STRENGTH - QUICKER & EASIER
P: A strength of using volunteer sampling is that it tends to be a quicker and easier process.
E: In this way, participants generally approach the researcher rather the other way around.
E: This means that the technique requires minimal effort and input on behalf of the researcher.
L: As a result, this makes obtaining a sample quicker and easier, in comparison to other methods.
LIMITATION - BIAS
P: A drawback of volunteer sampling is that there are issues with bias.
E: Very often it is a particular type of person that is likely to take part in research as only those who see the advert will come forward to participate.
E: Furthermore, those individuals who are more curious or inquisitive by nature may volunteer more readily.
L: Therefore, the sample is likely to be biased and not representative of the target population, which makes generalisation of the findings more difficult.
