Participants Flashcards
Target population?
Refers to the group of individuals a researcher is interested in, for example people above the age of 65 or A level students in the North East
What is a sampling frame?
Refers to the smaller group from the target population the researcher is going to sample their participants from e.g residents in a retirement home or QE students
Sample group definition?
Refers to participants actually used on the research, this is a sample taken from the sampling frame
Most representative sampling technique to least representative
Stratified/ Quota ⬇️ Random, Systematic ⬇️ Snowball, Opportunity ⬇️ Self selected
Least effort/ time to most effort
Self selected ⬇️ Snowball, opportunity ⬇️ Random, Systematic ⬇️ Stratified, Quota
Random sampling exp
- either get a list of all ppl in the target population, write all names on a piece of paper then place into a hat, select the number of ppts required OR enter names into a random computer generator, click button # number of times to get number of ppts needed
Random sampling advantages?
- unbiased = everyone in target audience has equal chance of getting selected = the sample should be more representative and findings more generalisable to the target pop than opportunity samples.
- compared to OS, less chance of researcher bias as random selection tech chooses ppts rather than the researcher themselves
Random sampling disadvantages?
- time consuming as researcher must identify everyone in the target group and select ppts at random unlike OS -> is quick and easy
- still may result in a biased sample - possible that random selection may result in a ‘freak’ unrepresentative sample unlike stratified which selects ppts from each strata in proportion to the rate they appear in the target audience
How does stratified sampling work?
- subgroups or strata within a target population are identified (e.g boys, girls, age groups) PPTS ARE GAINED FROM EACH STRATA IN PROPORTION TO THE RATE THEY APPEAR IN THE TARGET POPULATION
then: selection from the strata is done using a RANDOM technique
Strengths of stratified sampling?
+most REPRESENTATIVE sampling method as there is a PROPORTIONAL representation of subgroups therefore findings can be generalised to the target population.
+ COMPARED TO OPPORTUNITY SAMPLING there is less chance of researcher bias as the random technique, e.g. using random number generator, chooses the pts rather than the researcher themselves
Weaknesses of opportunity sampling?
_ Very Time consuming as all the subgroups need to be identified and then selected at random UNLIKE self-selected where ppts come forward themselves to take part in research
_ Even though this technique will select the most representative sample group of the population compared to other techniques, it is still likely that there will be some bias as not all subgroups or strata can be identified
how does QUOTA sampling technique work?
subgroups or strata within a target population are identified )e.g. boys, girls, age group). Ppts are gained from PRE-SET NUMBERS from each of the strata in PROPORTION to the rate that they appear in the target population
THEN: selection from the strata is done using a NON RANDOM TECHNIQUE
how does Snowball sampling technique work?
find one or a few Ppts - they rgeb recruit further ppts from amongst people they know
strengths of Quota sampling?
+ most representative sampling method as there is a proportional representation of subgroups therefore findings can be generalised to the target population
+ quicker than using a STRATIFIED sampling technique
weaknesses of Quota sampling?
_ Very time consuming as all the subgroups have to be identified and the selected UNLIKE SELF SELECTED where ppts come forward themselves to take part in research
_ May still contain an element of RESEARCHER BIAS as the non random technique is used to select the ppts in each quota - the researcher may identify ppts in each quota that may support their hypothesis
Strengths of snowball sampling?
+ useful at gaining access to difficult to reach ppts for example people with addictions meaning it may be the most appropriate technique for gaining ppts to researxc some behaviours
+ appropriate when the sampling frame is unknown
Weaknesses of snowball sampling?
_ unlikely to be representative as it uses friends/ contacts of initial ppts meaning it may be difficult to generalise the findings as they will be from similar groups
_ more time consuming compared to opportunity sampling technique as the researcher needs to wait for ppts to refer other ppts
how does opportunity sampling work?
Choosing ppl who are available at the time e.g. people walking past in the street
Strengths of opportunity sampling?
+ quick and easy method of gaining ppts as the researcher is choosing who is available at the time UNLIKE stratified sampling which requires each strata to be identified then PPts selected at random
+ appropriate to use when the samopling frame is unknown - such as ppl in a shopping centre. It is IMPOSSIBLE to use some other sampling techniques such as RANDOM or STRATIFIED when you don’t know who will be there at the time
Weaknesses of opportunity sampling?
_ likely to result in a BIASED SAMPLE as it is drawn from a small section of the population who are at the same place at the same time and are likely to share similar characteristics, e.g. students who use the common room. Therefore it will be unrepresentative and unlike a stratified sample which selects from across a sampling frame
_ INCREASED CHANCE OF RESEARCHER BIAS as they may only approach ppts who they think fit their aims/ hypothesis lowering the INTERNAL VALIDITY UNLIKE RANDOM sampling which gives everyone an equal chance of being selected
how does self selected sampling work?
Advertise for ppts in a newspaper , on a noticeboard or the internet. ppts then VOLUNTEER to take part
Strengths of self selected sampling?
+ Seen to be more ethical than other sampling techniques as you are surer you have ppts consent as they have volunteered for the study UNLIKE RANDOM SAMPLING where ppts may feel obliged to take part as they have been selected
+ Quick and easy method of gaining pts bc the researcher has to place the advert and then wait for the ppts to volunteer UNLIKE STRATIFIED which is very time consuming as requires each strata to be identified then ppts selected at random
Weaknesses of self selected sampling?
_ prone to volunteer BIAS as it may reult in a biased sample as it may be that only certain types of ppl are likely to volunteer e.g. extroverts or highly motivated ppl
. so, sample may be unrepresentative making it dificult to generalise findings to target pop
_ compared to other sampling tech you may be more LIKELY TO GET DEMAND CHARACTERISTICS as volunteer are more age to help the researcher find evidence to support their aims
How does systematic sampling work?
Use a pre-determined system (e.g. every 14th or 20th person) to select every nth ppt from the target population
Strengths of systematic sampling technique?
+ less chance of bias as ppts are selected using an OBJECTIVE SYSTEM e.g. every 10th person meaning UNLIKE OPPOR SAM where the researcher may approach ppts who suit their aims
+ Quicker sampling technique than stratified sampling as you do not need to establish the proportions different groups within the target population
Weaknesses of systematic sampling technique?
_ still may result in a biased sample - it is possible that the system may result in a ‘freak’ unrepresentative sample UNLIKE STRATIFIED which selects ppts from each strata in proportion to the rate they appear in the target population
- Not practical when the sampling frame is unknown, such as drug addicts, where a snowball or volunteer sample may be more appropriate
