Sampling /Sampling Techniques Flashcards
what are the different types of sampling?
- opportunity sample
- random sample
- stratified sample
- systematic sample
- volunteer sample
what is an opportunity sample?
recruiting people who are most convenient/most available
what is a random sample?
participants are randomly selected using random techniques
- lottery method (names out of a hat)
- random number table
- random number generator
what is a stratified sample?
subgroups within a population are identified (age, gender etc), participants are obtained from each subgroup in proportion to occurence in population
what is a systematic sample?
use predetermined system to select participants, numerical interval is applied constantly
what is a volunteer sample?
advertise on a newspaper/noticeboard/internet
what is a strength of opportunity sample?
easiest method because you find first suitable participants you can find, less time to locate sample
what is a limitation of an opportunity sample?
biased because sample is drawn from small population
what is a strength of random sampling?
unbiased, all member of population have equal chance of being selected
what is a limitation of random sampling?
need to have a list of all members of the population then contact those selected, takes time
what is a strength of stratified sampling?
likely to be more representative than other sampling methods because there is a proportional and randomly selected representation of subgroups
what is a limitation of stratified sampling?
very time consuming to identify subgroups, then randomly select participants and contact them
what is a strength of systematic sampling?
unbiased as participants are selected using an objective system
what is a limitation of systematic sampling?
not fully unbiased unless you select a number using a random number method and start with this person and then select every nth person
what is a strength of volunteer sampling?
gives access to variety of participants which may make sample more representative and less biased
what is a limitation of volunteer sampling?
may be biased as participants are likely to be more highly motivated and/or with extra time on their hands
- results in volunteer bias
What is quota sampling?
- Work out main demographic characteristics of your population and ensure that your sample is a fairly accurate scaled down vision of the population ‘
- is not random
- researcher aides on now many people are going to represent each category and find the right number of people until quota is filled
What is snowball sampling?
- researcher selects key individuals and these contacts greate more contacts and so on
- used when other sampling techniques would be ineffective
What is cluster sampling?
-‘Clusters’ or participants are randomly selected and auto individuals within me cluster participate in the research
- multi stage sampling is a form of Auster sampling where 2 random samples are selected, stage 1: selects clusters, stage 2: p’s within clusters are randomly selected
what does the term ‘target population’ refer to?
all members of a group you are interested in studying
what is a sample?
a smaller group selected from all the people in your chosen target population
what is generalisation?
- ability to generalise findings
- ability to apply findings beyond particular individuals studied
what is sampling bias?
when the sample does not have generalisability and external validity e.g. sample not randomly selected
what factors may create sampling bias?
- often difficult to recruit participants and may have to be bribed in some way
- sometimes force/coercion is used
- some participants will volunteer for various reasons
