INFERENTIAL STATISTICS

• two - tailed test


  type of test used when the study has a non directional hypothesis
• one - tailed test


  type of test used when study has a directional hypothesis
• significance level

  usually set at 0.5%, meaning there is a 5% possibility the results did occur by chance
• why is statistical testing used in psychological research

  to determine the likelihood that the difference they found occured by chance
• Significant


  term for data that could not have arisen by chance, or is extremely unlikely to have arisen by chance
• critical value


  value a test statistic must reach in order for null hypothesis to be rejected
• interval level


  data that is measured using equal intervals eg. number of correct answers on an IQ test
• non - parametric tests


  used to analyse data that is nominal or ordinal
• parametric tests


  used to make conclusions using mean and standard deviation, makes them a more powerful test
• nominal data


  data grouped into separate categories eg. smoker, non-smoker
• ordinal data

  data ordered in some way where difference between participants isn't the same eg. height of participants