research methods

• what is an aim


  identifies the purpose of the investigation
• what is a hypothesis

  precise and testable statement of what the researcher thinks will happen
• what is an independent variable


  variable that is manipulated
• what is a dependent variable 


  variable that is measured
• what is a test of difference 


  the experiment is looking for a difference between 2 variables e.g men and women
• what is a test of correlation

  the experiment is looking for a relationship between the co-variables correlating with an increase/decrease
• what is a directional hypothesis


  when there is previous research then a specific outcome can be predicted e.g women are more intelligent
• what is a non-directional hypothesis 


  when there is a lack of research, there is a prediction that the DV will change but no knowledge of what condition will cause this change e.g there will be a difference in intelligence between males and females
• what is a controlled variable

  variables which the researcher will successfully ensure does not affect the DV
• what is an extraneous variable

  nuisance variable which does not vary systematically with the DV
• what is a confounding variable

  varies systematically with the IV therefore we do not know what caused the change in DV
• what are systematic errors and give some examples 


  confounding variables that consistently affect all members of the sample

  • situation e.g noise + temp
  • measurement errors e.g broken scales
• what are random errors and give some examples

  extraneous variables that doesn't have any consistent effects across the entire population

  • situation e.g noise + temp
  • participant differences e.g age and IQ
• what are demand characteristics 


  participants are influenced by cues indicating the purpose of the experiment

  • pleaseU effect
  • screwU effect
  • social desirability
• what are investigator effects

  researchers have expectations of the outcome and this influences the participants' behaviour

  e.g facial expressions/design choices
• what are order effects

  when participants' responses are affected by the order of the condition in which they were exposed

  e.g boredom/practise/fatigue
• what are participant variables 


  any characteristic or aspect of a participant's background that could affect the study
• what are the 4 types of ways of controlling variables

  • randomisation
  • standardisation
  • random allocation
  • counterbalancing
• randomisation 


  randomise the material introducing chance therefore taking control away from observer
• standardisation


  identical location and instructions are standardised 

  • not leading to a specific outcome
• random allocation 


  assigning participants to groups with a random number generator
• counterbalancing

  • sample is divided in half
  • 2 conditions in a different order A+B OR B+A
  • neutralises order effects
• lab experiment 


  An experiment that takes place in a controlled environment where the researcher manipulates the IV and records the effect on the DV while maintaining strict control of extraneous variables
• strengths of lab experiment

  • easily replicated 
  • high control over confounding and extraneous variables
• weaknesses of lab experiment

  • lacks mundane realism 
  • lacks ecological validity
• field experiment


  experiment conducted in a natural environment manipulating the IV to see the effect on the DV
• strengths of field experiment

  • high ecological validity 
  • mundane realism
• weaknesses of field experiments

  • less control over extraneous variables
  • reduces internal validity 
  • harder to replicate 
  • ethics (consent)
• natural experiment

  an experiment that occurs in a natural setting measures the difference from 2 IV levels
• strength of natural experiment

  • high external validity 
  • limits demand characteristics
• weaknesses of natural experiment

  • can not be replicated 
  • lack of control over variables
• quasi experiment

  pre-existing from natural IV e.g gender and age and the researcher examines the effect of this on DV
• strengths of quasi experiments

  • allows comparisons between types of people
  • high ecological validity
• weaknesses of quasi experiments

  • lack of control over variables 
  • not replicable
• independent groups

  division into 2 groups and each group does a different condition
• strength of independent groups

  • not affected by order effects
  • not affected by demand characteristics
• weakness of independent groups

  participant variables as there are different participants in each condition
• repeated measures


  all participants take part in all conditions of the experiment
• strength of repeated measures

  reduces participant variables
• weakness of repeated measures

  • order effects 
  • demand characteristics