Samples

Ordered in a certain way e.g. alphabetically or by age and then every nth person is chosen 

Can give an unbiased sample from large populations 

Sometimes systems can mean that popualtions are still biased e.g. it could turn out that every 10th person might all be males under 30 

Exact rerpresentation of target population but on a smaller scale e.g. If 5% of the target population is left handed then 5% of the sample must be left handed too 

Deliberate effort is made to make the sample representative of the target population

Time consuming to calculate proportions and they can still be unrepresentative of the target population due to researcher bias (ask until you get the number you want)

Gather all participants and chose the same number as the sample by e.g. picking out a hat 

Provides the best chance of an unbiased, representative sample for large populations 

Time consuming to create a list of every single participant with large populations

Group the participants in a certain way e.g. height or age and chose x number from each group to represent your target population 

Deliberate effort is made to make the sample representative of the target population 

Time consuming t identify the suitable sub-catagories then choose to make it represnative 

Asking anybody availible and willing to participate e.g. asking people in the street 

Quick, convinent, and econimical. It is the most commonly used 

Very unrepresentative and often includes researcher bias as they wil choose those that seem that they will most likely be helpful 

Putting an advert in e.g. a newspaper and allowing the participants to volunteer themselves. It often has a financial incentive 

Convinient and ethical if it includes informed consent 

Unrepresentative as it leads to participant bias e.g. only acedenmics will read journals like Newhaven

A small number of participants ask people that they know that you want to study e.g. prostitutes to participate and they too ask others until you get your target population 

Useful way of finding the type of particiant you want e.g. prostitutes that may not volunteer to participate otherwise 

Can be biased people, people with friends are most likely to be selected. Some people may not want to be found by psychologist 

Have a list of certain behaviours you want to observe e.g. punching the wall and make a tally chart to record the number of times it occurs 

Looking for certain behaviours e.g. shouting at another person but only recording it every nth minute