experiments

• four types : lab, field, quasi, natural
• lab - independent variable manipulated by researcher

  -all other variables which may influence are held constant or eliminated

  -Ps randomly allocated to experimental conditions
• field - independent variable manipulated

  -study carried out in Ps natural environment
• quasi - independent variable is condition that already exists

  -difference between people already existing

  -conducted in lab or field
• natural - independent variable naturally occuring

  -measures change that will happen anyway

  -two conditions of IV are often before & after a natural change
• field strengths - validity (in natural setting)
• field limitations - less control than lab experiments

  -extraneous variables can distort findings - low internal validity
• natural & quasi strengths - high ecological validity
• natural & quasi limitations - lack of control

  -not replicable
• hypothesis - clear statement of what you think WILL happen
• null hypothesis - predicts there'll be no difference
• 1 tailed hypothesis - predicts a difference and tells us what difference will be
• 2 tailed hypothesis - predicts a difference but doesn't tell us what difference will be
• writing structures for hypothesis :

  • 1 tailed = IV DV IV
  • 2 tailed = DV IV IV
  • null = DV IV IV
• independent variable - variable that's manipulated or changed by experimenter
• dependent variable -variable being measured
• extraneous variables - any variable other than IV that could affect the DV

  -needs to be controlled