sampling Flashcards
population
a group of people who are the focus of the researcher’s interest, from which a smaller sample is drawn
sample
a group of people who take part in a research investigation
the sample if drawn from a population and is resumed to be representative of that population
sampling techniques
the method used to select people from the population
bias - sampling
in the context of sampling, when certain groups are over or under-represented within the sample selected
generalisation - sampling
the extent to which findings and conclusions from a particular investigation can be broadly applied to the population
this is possible if the sample of participants is representative of the target population
random sample
every member of the target population has an equal chance of being selected
systematic sample
every nth person is chosen from a list
stratified sample
the proportions of people in population subgroups (strata) are reflected in the sample
opportunity sample
whoever is available at the time of sampling will be included
volunteer sample
participants ‘self-select’
random sample eval
- unbiased - confounding or extraneous variables should be equally divided between different groups - enhancing internal validity
- difficult and time-consuming
- may still be unrepresentative - laws of probability suggest random sampling more likely but not 100% of case
- participants may refuse to take part so becomes more like volunteer sample
systematic sample eval
- objective as researcher has no influence over who is chosen
- time-consuming and may refuse to take part so becomes a volunteer sample
stratified sample eval
- designed to accurately reflect the composition of the population - generalisation of findings possible
- not perfect - identified strata cannot reflect all the ways people are different so complete representation not possible
opportunity sample eval
- convenient - less costly in terms of time and money than random sampling - list of population not required
- two forms of bias - unrepresentative of the target population as drawn from specific area so cannot be generalised and researcher bias as complete control over selection of participants
volunteer sample eval
- easy as required minimal effort so less time-consuming than other forms of sampling - participant more engaged
- volunteer bias - may attract a certain profile of person - lacks generalisability