research methods

• four different types of experiment


  laboratory

  field

  quasi

  natural
• definition - laboratory experiment


  conducted in highly controlled environments where the researcher manipulates the IV and decides all characteristics of the experiment
• strengths - laboratory experiment


  * high control over confounding and extraneous variables so most effects on DV are due to IV manipulation

  * reliable as replicability is high which increases validity of experiment
• limitations - laboratory experiment


  * low external validity

  * demand characteristics shown

  * low mundane realism - artificial so doesn’t represent everyday experiments
• definition - field experiment


  conducted in a natural environment and the researcher manipulates the IV
• strengths - field experiment

  * high ecological validity - environment is natural

  * more valid and authentic behaviour produced
• limitations - field experiment


  * loss of control on confounding and extraneous variables

  * ethical issues - unaware being studied
• definition - natural experiment


  naturally occurring and manipulated IV is examined by the effect of natural occurring event / situation on DV
• advantages - natural experiment


  * high external validity - real-world issues

  * provide opportunities into research that may not be undertaken for practical of ethical issues
• weaknesses - natural experiment


  * rarely occurring

  * pp may not be randomly allocated

  * cannot claim IV has caused observed change
• definition - quasi experiment


  naturally occurring IV is investigated and already in pre-existing groups based on characteristics which is controlled. the researcher examines the effect this variable has on the
• advantages - quasi experiment


  * replication - increases validity
• limitations - quasi experiment


  * cofounding variables

  * cannot claim IV has caused observed change
• definition - null hypothesis


  states there is no significant difference (any difference found is due to chance)
• definition - independent variable


  the variable that is manipulated by the researcher and creates different conditions
• definition - dependent variable

  variable that is measures and is produced by the IV manipulation (quantitative + operationalised)
• what variable is operationalised


  DV
• definition - operationalised


  specific unit of measurement
• what is a directional and non-directional hypothesis examples of


  experimental hypothesis
• definition - hypothesis


  a clear, precise testable statement that states the relationship between the variables to be investigated
• definition - directional hypothesis


  states direction of the different of relationship between variables (previous research shows direction)
• definition - non-directional hypothesis


  does not state the direction of the difference in relationship between variables
• what hypothesis is one-tailed


  directional hypothesis
• what hypothesis is two-tailed

  non-directional hypothesis
• why would a directional hypothesis be chosen over a non-directional hypothesis

  provides a more precise and focussed prediction
• how to get rid of extraneous variables


  keep them controlled
• how to get rid of confounding variables


  eliminate them
• definition - extraneous variables


  the variable that is not being manipulated or measured, but can still effect the outcome of the experiment
• definition - confounding variable


  varies systematically with IV and affects everyone. cannot tell if CV or IV has manipulated the DV
• three types of experimental design


  independent groups

  repeated measures

  matched pairs
• definition - independent groups


  different groups of participants take parts in one condition of the experiment each
• strengths - independent groups


  * order affects are not a problem as no practice

  * pp less likely to show demand characteristics
• limitations - independent groups


  * reduces validity

  * less economical - more pp is needed so more time consuming and expensive
• definition - repeated measures


  all pp take parts in all conditions of the expirement
• strengths - repeated measures


  * high validity as variable conditions are controlled

  * less time recruiting pp because less are needed
• limitations - repeated measures


  * order affects

  * boredom / fatigue / deterioration due to repeating

  * demand characteristics
• definition - matched pairs

  pp are paired together on variables relevant to experiment (eg : IQ)

  each pp is then allocated a different condition
• strengths - matched pairs

  * limits confounding variables of participant variables

  * order affects + demand characteristics are less of a problem - only experience single condition
• limitations - matched pairs


  * pp can never be matched exactly

  * expensive - pre-testing required to match pp

  * time consuming
• definition - counterbalancing


  each experiment is experienced last once within the different conditions so order effects occur on all conditions and not just one (fair test)