BM CH5

• three common types of measure

  self-report, observational, physiological
• self-report measures


  operationalises a variable by recording people's answers to questions about themselves in a questionnaire or interview
• self-report in children...


  may be replaced by report of a guardian or teacher
• observational measures aka


  behavioural measures
• observational measures


  operationalises a variable by recording observable behaviours or physical traces of behaviours
• example of 'physical traces' of behaviour

  tooth marks on pencil for stress
• physiological measures


  operationalises a variable by recording biological data such as brain activity, hormone levels, or heart rate
• physiological measures require...


  equipment such as an fMRI
• physiological measures must be...

  validated in another way e.g. self-report
• categorical variables


  levels = categories e.g. gender
• categorical levles must be assigned...

  numbers for data processing purposes
• quantitative variables


  meaningful numbers e.g. height
• quantitative variable scales


  ordinal, interval, ratio
• ordinal scale


  ranked order, intervals may be unequal
• interval scale


  equal intervals, no 'true zero
• ratio scale


  equal intervals, 'true zero
• reliability


  consistency of measurement
• validity


  the extent to which a test measures or predicts what it is supposed to
• types of reliability


  test-retest, interrater, internal
• test-retest reliability


  researcher gets consistent scores each time they use the measure
• reliability most relevant to relatively stable constructs

  test-retest
• interrater reliability


  consistent scores no matter who measures the variable, uses two+ independent observers
• reliability most relevant to observational measures

  interrater
• internal reliability (internal consistency)

  participant gives consistent pattern of answers no matter how the question is phrased
• internal reliability only applies to...

  self-report measures with multiple items
• reliability is effectively...


  an association claim
• scatterplots can be used to...

  show interrater (dis)agreement, visualise test-retest reliability
• correlation coefficient, r


  indicates how close the points are to a line drawn through them
• r takes a value between

  -1 and 1
• a negative r value is...


  rare and undesirable
• Cronbach's alpha


  a correlation-based statistic that measures a scale's internal reliability (closer to 1 = more reliable)
• validity of abstract constructs

  face, content, criterion
• face validity


  whether the operationalisation is plausible
• content validity


  the extent to which is captures all parts of the construct
• criterion validity


  the extent to which a measure is correlated with a behaviour or concrete outcome that it should be related to
• criterion validity is especially important for...

  self-report
• criterion validity can provide strong evidence for...

  construct validity
• known-groups paradigm


  whether scores on the measure can discriminate among a set of groups whose behaviour is already well understood
• convergent validity


  scores on the measure are related to other measures of the same construct
• discriminant/divergent validity


  scores on the measure are not related to other measures that are theoretically different