research methods

• Independent variable (IV)


  the variable directly manipulated by the researcher.
• Dependent variable (DV)


  the variable being measured in a study.
• Operationalisation


  making the variables in an investigation detailed and specific.
• Extraneous variable


  a variable that is not controlled, which could affect the results of a study.
• Confounding variable


  an extraneous variable that affects the results of the study so that the effect of the IV is not truly being seen.
• Situational variable


  an extraneous variable present in the environment of the study.
• Order effects


  when participants improve or worsen in the second condition because they have practised or become fatigued.
• Demand characteristics


  when the participant alters their behaviour in response to the perceived aims of the investigation.
• Investigator effect


  when a researcher unintentionally gives clues to participants, altering their behaviour.
• Participant variables


  extraneous variables specific to the participants of an investigation, for example their mood, ability or personality.
• Standardised procedure


  where the procedure of a study is the same across all conditions.
• Counterbalancing


  where half of the participant group experience condition A then condition B, while the other half experience condition B then condition A.
• Randomisation


  when participants are randomly assigned to condition A or B as their first or second test condition.
• Single-blind technique


  when information about the study is withheld from participants.
• Double-blind technique


  when the aims of the study are withheld from both participants and researchers.
• Random allocation


  when participants are randomly assigned to a condition of the study.
• Null hypothesis


  a prediction that the results will fail to show any difference (or relationship) that is consistent or systematic.
• Experimental hypothesis


  a prediction of the outcome of a study based on what is expected to happen.
• Directional hypothesis


  a hypothesis that predicts the direction the results will go in.
• Non-directional hypothesis


  a hypothesis that predicts that a difference/relationship will be found, but does not specify what the difference/relationship will be.
• Target population


  the group of people being investigated in a study.
• Sample


  a selection of the target population that is directly studied in an investigation.
• Sampling method


  a technique used to gather a representative group of people as a sample from the target population.
• Random sampling technique


  a technique used to gather a random sample of participants from the target population.
• Stratified sampling technique


  a technique that ensures subgroups of the target population are proportionately represented in a sample.
• Opportunity sampling technique


  a technique that recruits participants who are readily available at the time.
• Volunteer sampling technique


  a technique that asks for participants by placing an advert for volunteers.
• Sample error


  when a sample differs in qualities from the target population it intends to represent.
• Biased sample


  when the sample recruited is made upof a particular type of person, which may not reflect the target population.
• Research design


  how participants are allocated to the conditions of a study.
• Experimental design


  the name given to research design when used in an experiment.
• Independent measures design


  participants are split into groups, with each group tested in only one condition of a study.
• Repeated measures design


  the same participants are used in all conditions of a study.
• Matched pairs design


  different participants are used in each condition of the study, but are matched for likeliness on important characteristics
• Reliability


  the consistency of an outcome or result of an investigation (a measure).
• Validity


  whether the test measures what was intended.
• Internal validity


  whether the measures used in a test genuinely test what they were designed to test.
• External validity


  whether the findings are generalisable to the target population.
• Qualitative methods


  ways of conducting research that find out new information rather
• than testing a prediction; often resulting in gathering qualitative data.