Research methods & case studies (SAMPLING METHODS (STRATIFIED (The…
Research methods & case studies
• Conducted in artificial environments, constructed by the experimenter.
• The researcher manipulates the independent variable (IV) and measures the dependent variable (DV).
• In criminological psychology, the IV is manipulated to investigate things such as the effect of a specific factor (weapon presence/leading questions).
• The DV is the testimony or recall given by the witness.
Low ecological validity
Demand characteristics are highly possible due to expectation
Can cause distress even though it isn't real
They can be easily replicated
High levels of control over extraneous variables and the IV
Cause and effect can be established easily
Less ethical concerns than if it were real life incidents
are an in depth investigation into a single person, group or event. In criminological psychology it usually involves looking into a case of an offender. They are particularly useful to help understand why someone has committed the crime and allow a clinician to develop understanding of further factors causing specific behaviour. They also use an IV and DV as with experiments
Gathers data from many different sources
Information rich in detail
Lacks generalisability & representativeness
The researcher identifies the different types of people that make up the target population and works out the proportions needed for the sample to be representative.
Gathering such a sample would be extremely time consuming and difficult to do (weakness). This method is rarely used in Psychology. However, the strength is that the sample should be highly representative of the target population and therefore we can generalize from the results obtained.
The sample consists of people who have volunteered to be in the study.
A strength is this often achieves a large sample size through reaching a wide audience, for example with online advertisements. However, those who respond to the call for volunteers may all display similar characteristics (such as being more trusting or cooperative than those who did not apply) thus increasing the chances of yielding an unrepresentative sample (weakness)
Everyone in the entire target population has an equal chance of being selected.
The strengths are that your sample should represent the target population and eliminate sampling bias, but the weakness is that it is very difficult to achieve (i.e. time, effort and money).
Uses people from target population available at the time and willing to take part. It is based on convenience.
This is a quick way and easy of choosing participants (strength), but may not provide a representative sample, and could be biased (weakness).
A systematic method is chosen for selecting from a target group, e.g. every fourth person in a list could be used in the sample.
Assuming the list order has been randomised, this method offers an unbiased chance of gaining a representative sample (strenghth). If the list has been assembled in any other way, bias may be present. For example if every fourth person in the list was male, you would have only males in your sample (weakness).
• Conducted in natural settings
• The IV and DV are still manipulated and measured
• Most of the situation is realistic other than the test of the effect such as completing a questionnaire or answering questions immediately afterwards
Ethical issues such as stress
Harder to control
Behaviour is more likely to reflect real life
Higher ecological validity
Lower demand characteristics