Research Methods

• Independent variable 


  The variable directly manipulated by the researcher
• Dependent variable


  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 practiced 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 that is consistent or systematic
• Alternative (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 it will be
• Experimental hypothesis


  The name given to a hypothesis when used in field and laboratory experiments
• 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
• Generalisability 


  The extent to which the results of a study represent the whole population, not just the sample used
• Sampling method 


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


  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
• Sample error 


  When a sample differs in qualities from the target population it intends to represent
• Volunteer sampling technique


  A technique that asks for participants by placing an advert for volunteers
• Biased sample


  When the sample recruited is made up of a particular type of person, which may not reflect the target population
• Opportunity sampling technique


  A technique that recruits participants who are readily available at the time
• 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
• Independant 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 likeness 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 generalisble to the target population