Sampling Methods: Target Populations & Samples (AQA GCSE Psychology)

A sample consists of the participants who will take part in the research 

A sample is taken from the population that is relevant to the research topic. e.g.

• Teen mothers

• Office workers in Scotland

• People aged 60-85 years old who have dementia

A target population tends to have distinct characteristics which are of particular interest to the researcher

Once the target population has been identified the researcher draws a sample from that population

Often a sample is taken from a population which is more generalised (i.e. not so specific) than a highly specific target population, e.g.

• Research which investigates the effect of loud music on concentration can draw its participants from a wide range of people

• Research on the duration of STM does not require a highly specific sample (generally anyone from the age of 18-60 would suffice)

Researchers use different sampling techniques 

Once the research process is over the researcher analyses their findings and draws conclusions based on these findings

One of the issues in using a small, limited or highly specific sample is that it is very difficult to generalise the findings beyond the scope of this sample, e.g.

• A sample of 25 office workers from Glasgow in Scotland does not represent office workers in other parts of Scotland or the UK therefore the findings from such a sample can only apply to other office workers (within the same age range as those in the sample) from Glasgow

• To make the sample more representative the researcher should use a cross-sectional sample e.g. office workers from other parts of the UK

The data from a small sample e.g. 25 office workers is not robust therefore the quantitative findings are less likely to stand up to analysis via statistical methods i.e. the researcher may find that the IV has not affected the DV (which a waste of their time and resources)

Larger samples are more robust and reliable data

There are several reasons as to why small samples may be used in psychological research:

• Running research is expensive so it may only be possible to conduct a snapshot study with a small sample

• It may be difficult to find enough participants to take part in the study, particularly if the research requires a very specific sample

• The researcher does not have very much time in which to conduct the study so they use whichever participants are most convenient e.g. university students

• Some types of qualitative research such as case studies and interviews tend to use very small samples but these are the exception; most research studies require large samples 

Any sample which uses participants who, for example, are from the same town, are the same age, possess similar personality traits, is a biased sample i.e. the results are difficult to generalise