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Participants(Ppts) (Sampling Techniques (7) (Opportunity (Definition =…
Participants(Ppts)
Sampling Techniques (7)
Opportunity
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Advantages : + Quick and easy to gain Ppts unlike stratified sampling where each strata needs to be identified before selecting Ppts (randomly) . + Appropriate to use when sampling frame is unknown e.g. people at the shopping centre (won't be able to use stratified or random)
Disadvantages : - likely result in biased sample = small section of population are at the same place = similar characteristics. Therefore not a great representative unlike stratified which selects from across the sampling frame. - Increase chance of researcher bias as they may approach Ppts who are fit for their aims/ hypothesis lowering the internal validity unlike random which gives everyone equal chance of being selected
Self-selected
Definition = Advertise for Ppts in a newspaper, on a noticeboard or the internet. Ppts then volunteer to take part
Advantages : + Seen to be more ethical than other sampling techniques as they get Ppts consent as they volunteer unlike random where Ppts feel like they are obliged to participate . + Quick and easy method of gaining Ppts because Ppts volunteer unlike Stratified which is time consuming as they need to know identity then randomly select Ppts
Disadvantages : - Prone to volunteer bias as only certain types of Ppts volunteer e.g. extroverts (outgoing personality) or highly motivated people. Thus unrepresentative and difficult to generalise target population. - Compared to other sampling technique = more likely to get demand characteristics as volunteer are more eager to help researcher find evidence to support their aims
Systematic
Definition = Use a pre-determined system (e.g. every 14th or 20th person) to select every nth Ppt from the target population
Advantages : + less chance of bias as Ppts are selected using an objective system e.g. 10th person meaning unlike opportunity sampling the researcher may approach ppts who suit their aim . + Quicker sampling technique than stratified
Disadvantages : - May result in a biased sample = result in 'freak' unrepresentative sample unlike stratified which select ppt from proportion of target population . - not practical when sampling frame is unknown, such as drugs addicts, where snowball of volunteer sample maybe more appropriate
Random
Definition = Get a list of all the people in the target population.Write all their names down on a piece of paper and place it in a hat, select the number of Ppts you require from the hat
Advantages : + Unbiased as everyone in target population has an equal chance of being selected meaning the sample should be more representative and findings more generalisable to the target population than opportunity samples. + Compared to an opportunity sampling there is less chance of researcher bias as the random selection technique e.g. names in a hat, chooses the Ppts rather than the researcher themselves
Disadvantages : - Time consuming as researcher must identify target population then select Ppts randomly unlike Opportunity sampling which is quick and easy . - still may be bias sample = possible that random selected Ppts in a 'freak' unrepresentative sample unlike stratified which selects Ppts in proportion.
Stratified
Definition = Subgroups or strata within a target population are identified (e.g. boys and girls or 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
Advantages : + Most representative sampling as there is proportional representative of subgroups thus researcher can generalise target population. + Compared to Opportunity sampling there is less chance we of researcher bias as the random technique e,g, using random number generator, chooses the Ppts rather than the researcher themselves
Disadvantages : - very time consuming unlike self-selected where Ppts come forward themselves to take part in research. - Even though this technique will select most representative sample group of the population compared to other techniques, it's still likely that there will be some bias as not all subgroups or strata can be identified
Quota
Definition = Subgroups or strata within a target population are identified (e.g. boys and girls or age groups). Ppts are gained from pre-set numbers from each of the strata. THEN : selection from the strata is done using a non-random technique
Advantages : + most representative sampling method as there is a proportional representation of subgroups therefore findings can be generalised to the target population.. + Quicker than using stratified sampling technique
Disadvantages :- very time consuming as they need to identify subgroups unlike self-selected where Ppts come forward themselves. - may also contain element of researcher bias as a non-random technique is used to select Ppts in each quota - the researcher may identify Ppts in each quota that may support their hypothesis
Snowball
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Advantages : Useful at gaining to difficult to reach Ppts - e.g. people with addictions meaning it may be the most appropriate technique for gaining ppts to research some behaviours . + Appropriate when the sampling frame is unknown
Disadvantages : - Unlikely to be representative as it uses friends/contacts of initial Ppts meaning it may be difficult to generalise as they would being similar groups . - more time consuming compared to opportunity sampling technique as the researcher needs to wait for Ppts to refer other Ppts
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