Sampling

• Target Population- the entire set of people researchers want to generalise their results to
• Sample- the actual people who are selected to use
• Representative- an accurate reflection of a larger group
• Random- a sample of participants produced using a random technique such that every member of the target population being tested has an equal chance e.g. names out of a hat, online randomiser
• Random- pros, unbiased all members of the target population have an equal chance of selection. Cons, the researcher may still end up with a biased sample if the sample is too small
• Opportunity- a sample of participants produced by selecting the people who were most easily available at the time of the study e.g people walking in the street
• Opportunity- pros, easiest technique, takes less time and effort. Cons, inevitably biased (unrepresentative) because sample is drawn from a small part of the target population
• Volunteer- relies o people putting themselves forward/volunteering to make up the sample e.g. advertise on newspaper or noticeboard
• Volunteer- pros, more representative, less biased, access to a variety of participants. Cons, sample is biased "participant bias" more likely to be highly motivated and or have more time on their hands
• Stratisfied- the sub strata is of equal proportion to the target population, random technique
• Statisfied- pros, unbiased, all characteristics of a population are being tested. Cons, sample may be unrepresentative if all key features of the population are not identified, very time consuming to identify subgroups and select participants.
• Systematic- nth term picked randomly then applied through but only the first person(nth term) is selected randomly
• Systematic- pros, avoids investigator bias. Cons, possibly representative, difficult to obtain a list of entire target population and or if obtained some may be unavailable or unwilling