A sample is group of people who have been selected to take part in research; a small section of the population is used. If a sample is 
representative it must show the characteristics of the whole population within the small group selected, this allows researchers to obtain information about the population as a whole without having to investigate every member of society. A positive impact of representative sampling is that it also means that the research can be generalisable (the research findings can be used to make general assumptions about the groups and the population as a whole) thus allowing cost and time to be kept to a minimum.
However, an issue of representative sampling lies within the various methods of sampling, some methods are much less representative than others and therefore may not lead to accurate conclusions within the data. For example – purposive sampling (choosing people with particular characteristics that the researcher wants to study) may lead to a study being biased. Also, opportunity sampling (choosing the people that are available when a researcher is ready to carry out their research) may mean that a certain type of person is used when the research is undertaken.
