Aims and hypotheses

• Aim


  Specific statement about why the study is being carried out
• Hypothesis


  Testable statement about the outcome/findings of research
• Two types of testable statements:

  • Investigating difference
  • Investigating causal relationship
• Hypothesis of difference:

  • Experimental
  • IV + DV -> hypothesis based on difference in DV due to IV
• Hypothesis of causal relationships:

  • Both co-variables measured -> no IV or DV (variables go up/down at the same time, e.g. increase in one = decrease in the other + both are measured)
  • Hypothesis based on causal relationship
• Two types of hypothesis:

  • Null
  • Alternative (experimental)
• Null hypothesis (H₀):

  • States no significant relationship between investigated variables
  • Used to make disprovable precise prediction that nothing will happen
  • Falsifiability: null hypothesis = baseline expectation in statistical test (H₀ supported = no difference/relationship between X and Y -> any changes due to extraneous variables)
  • In difference investigation: "there will be no difference between IV and DV"
  • In correlational investigation: "there will be no relationship between co-variables"
• Alternative hypothesis (H₁) :

  • Statement predicting difference/relationship between IV + DV
  • Directional or non-directional
• Alternative directional hypothesis


  Specific difference/relationship predicted ('one-tailed')
• Alternative non-directional hypothesis


  Nonspecific difference/relationship predicted ('two-tailed')
• Operationalisation of hypotheses:

  • These hypotheses aren't actually used by psychologists when undertaking studies
  • Hypotheses not measurable = saying something is lesser/greater/different isn't making it clear how the accuracy of IV/DV is being measured
  • Objective research = measurable research
  • Making hypotheses measurable is vital -> 'operationalisation'