Sampling Flashcards
(22 cards)
Target population
-A target population is every member of the group that the researcher intends to study
-A target population can contain millions of people and the researcher cannot study all of them
samples + generalisability
-Researchers take small samples of participants from the larger target population
-The results/behaviours are assumed to generalise to all the members of the target population
-Whether or not the results are generalisable depends on how representative the sample is of the general population, therefore the sample should share characteristics with the target population (age, gender, ethnicity, education/income level)
Therefore the ideal sample are similar as possible to the target population
Random sampling
-Random sampling is when every member of the target population has a mathematically equal chance of being in the experiment’s sample
How to conduct random sampling
-The researcher gathers every name in the target population
-The researcher will then place all of these names into a container or into a computer database
-The researcher will then randomly select a number of names that fits the requirement of the sample
-These individuals will be in the sample
Advantages of random sampling
-Random sampling avoids researcher bias as the researcher is unable to pick which participants will form the sample that will be used in the study
-This avoids the possibility of the researcher choosing individuals for the sample because they think they will give a preferred result
Disadvantages of random sampling
-There is a possibility that the members selected randomly for the sample will be unrepresentative of the target population e.g too many members of one gender or no members of a minority
-Getting a list of names of everyone in the target population is difficult and time consuming
Systematic sampling
-Systematic sampling is when participants are chosen from a list of every member from the target population
-Every Nth participant on the list is chosen for the sample e.g every 5th , 10th, 100th name on the list
How to conduct systematic sampling
- The researcher needs to gather a list of names of all the members of the target population
- The researcher needs to select every Nth member of the population to be part of the sample e.g every 5th name on the list
-This continues until the sample requirements are met (enough people are chosen to continue)
Advantages of systematic sampling
Systematic sampling avoids researcher bias as the researcher is unable to choose which members of the target population will form the sample; this avoids the possibility that the researcher will pick participants from the target population because they think they will give produce preferred results
-If the list of members of the target population is pre-existing e.g a school or college register, this can be a quick and easy method of selecting a sample
Disadvantages of systematic sampling
-There is a possibility that this sampling method could produce an unrepresentative sample of the target population e.g too many of one gender or no members of a minority group
-If the target population is large it can be very difficult and time consuming to form a list of all the members of the target population
Opportunity sampling
-Opportunity sampling is when the researcher directly asks members of the target population to take part in the study
-This is most likely to be individuals that the researcher has easy access to and are familiar with
How to conduct opportunity sampling
-The researcher will directly ask members (that they have access to) of the target population to take part in the study
-Those that agree to take part in the study will be added to the sample until the participant requirement is met
Advantages of opportunity sampling
-Opportunity sampling is the fastest method of getting a sample for a study, reducing the time and cost of conducting research compared to other more complex sampling methods
Disadvantages of opportunity sampling
-The sample is unlikely to be representative of the target population as the researcher has most likely just chosen people that they have easy access to for example undergraduate students
-Since the researcher chooses which members of the target population will form the sample, this method of sampling may suffer from researcher bias. The researcher may choose individuals that they think will produce the preferred result (confirm their research hypothesis)
Volunteer sampling
-Volunteer sampling is when the participant (from within the target population) offers to take part in the study after finding out about the research (they are not directly asked by the researcher) this is likely after seeing an ad in the newspaper or online
How to conduct volunteer sampling
-The researcher will place advertisements in places that the target population are likely to see them e.g gym for fitness enthusiasts or pub for alcoholics
-The advertisement will include contact details and the researcher will include the participants into the sample once they have been contacted by the volunteer
Advantages of volunteer sampling
-Advertising can reach a very large number of individuals within the target audience, especially if the newspaper or website is widely read
-Volunteer sampling is an easy way of gathering a sample, as participants put themselves forward rather than the researcher having to seek them out individually and contact them directly; this makes it less difficult and less time consuming
Disadvantages of volunteer sampling
-The sample gathered from volunteer sampling may not be generalisable to the target population, this is because of volunteer bias; individuals that volunteer to take part in the study will likely have different characteristics to those in the target population e.g more friendly with more time on their hands
Stratified sampling
-Stratified sampling creates a sample that is representative of the target population
-The characteristics of participants in the sample group will be in proportion with those present in the target population
How to conduct stratified sampling
-Strata/subgroups will be identified along with their proportion (ethnicity, education level, gender etc)
-Random sampling will be used to select the number of participants required from within each stratum
-For example: a population is made up of 10% graduates and 90% non graduates- this would mean that there are 9 non graduates and 1 graduate in a sample of 10
Advantages of stratified sampling
-The sample is representative of the larger target population, therefore results with the sample should be generalisable to the target population
-Stratified sampling avoids researcher bias, as participants are randomly selected from within the stratum; this means that the researcher cannot choose participants that they think will give the preferred answer
Disadvantages of stratified sampling
-With stratified sampling, it is time-consuming to identify strata and then randomly select individuals from within each stratum
-Not ever characteristic can be included within a stratified sampling, meaning the researcher has to decide which strata is more important than others, potentially leading to bias
