AQA GCSE Psychology Unit 4 - Research methods

Aim

a statement that explains the purpose of a study

Independent and Dependent Variables

• The Independent Variable (IV) is the factor which is changed/manipulated

• Dependent Variable (DV), which is the variable being measured

Extraneous Variables

Variables which affect the DV but are not manipulated by the researcher

hypothesis

testable statement written as a prediction of what the researcher expects to find as a result of their experiment

Alternative and Null hypotheses

• The alternative Hypothesis is a hypothesis that states that the IV will affect the DV, wheras a null hypothesis states the opposite

Operationalisation

Clearly defining variables in terms of how they could be measured

Methods of standardisation

• instructions: ppts all recieve the same information

• procedures: the ppts environment/instructions/experience should be the same unless the difference is the independent variable

• randomisation: make sure there are no biases in procedures

Reliabilty

whether a study would produce similar results if repeated

Validity

• whether the reasearch measures what it should be

Types of Validity

• Internal validity: how sure we can be the IV affects the DV

• External Validity:how much does the study tell us about people real world behaviours

  • Populational validity: is the sample of ppts representative of the whole world

  • Ecological Validity: does the setting for the study reflect real life

Ethical Considerations

• informed consent

• anonymity and confidentiality

• voluntary participation

• protection from harm

• dont impose unreasonable demands

Sampling methods

• sampling is thr process of selecting a representative group for a study

• target populations is the group of induviduals from which the sample will be drawn from

Random Sampling

• all members of the target group have an equal chance of selection

  • +reasonable chance of acheiving a representative sample

  • - small minority groups in target group may distort results

  • - can be impractica to use a completeley random technique

Systematic sampling

• a systematic method is chosen for selection from a target group e.g. every fourth name

  • + assuming the list is randomised the method provides an unbiased representative sample

  • - if the list isnt randomised the method is biased

Stratified Sampling

• the sampler divides the target group into sections so the sample contains characteristics in a proportion representative of the target populations

  • + avoids misrepresentation

  • - takes more time and resources

Opportunity sampling

• participants who are acessible and willing to take part are targeted

  • + method is easy and inexpensive

  • - sample may not end up being representative

Quantative and Qualitative Data

• Quantative Data - data that involves words and numbers and has set answers

  • + easy to analyse

  • - lacks depth and detail

• Qualitative - data that starts out in words or pictures but can be turned into numbers

  • + has depth and detail

  • - hard to analyse

Primary and Secondary Data

• Primary Data - Data which has been collected firsthand by the researchers for the experiment

  • + data will suit the aims of the researcher

  • - takes more time and effort

• Secondary Data - Data that has already collected by someone else

  • + easy to access

  • - not tailored to the study

Experimental Design

The various ways in which participants can be organised into conditions in an experiment

Independent Groups Design

• ppts are allocated to one condition of the IV so there are separate groups for each condition

  • + can use same stimulus material in both groups

  • - unknown if induvidual differences are EVs

Repeated Measures

• ppts are involved in all conditions and their sets of data are compared. Half do one condition and then switch to the other

  • + measure for induvidual differences

  • - can’t use the same stimulus materials

  • - order effect

Matched Pairs

• ppts are allocated to one condition but they are matched to eachother on characteristics that may affect the DV e.g. age or sex

  • + comparing similar people without order effects

  • + can use same stimulus materials

  • - complicated to get matching people