3: Individual Differences

• Individual differences


  the differences that individuals have
• Personnel psychology:


  focuses on the scientific study and application of individual differences in the work place
• Psychometrics


  measuring different attributes of individuals
• Indirect approach to influencing behaviour


  focus on individual differences

  Psychological reactions are influenced by individual differences
• I-O Psychologists interest =


  limited to psychological differences. especially those related to work behaviour and/ or performance
• implicit science


  Implicit learning is defined as a type of long-term human memory that encompasses the subconscious knowledge or experience necessary to carry out a particular task (e.g. phonological processing, literacy skills or driving a car)
• MID


  measuring individual differences
• measuring


  Measuring individual differences [psychological testing/ psychometrics] is more complex as it involves measuring latent constructs [unseen or intangible attributes]
• reliabilty


  stability over time and internally consistent
• Stability over time/ Temporal stability


  Test-retest Reliability

  Calculated by correlating measurements taken at time 1 with measurement taken at time 2

  want measure to show the same result/similar at 2 different points in time then calculate the correlation

  want people to get the same score
• 3 characteristics of internal consistency


  Equivalent Forms of reliability

  Split-half reliability method

  Cronbach's Alpha
• IC: equivalent forms of reliability


  administering 2 different tests on 2 occasions

  Calculated by correlating measurement from the sample of individuals who complete two different forms of the same test
• IC: split half reliability method


  Pretend that instead of one test, there are two or more

  Problem: it depends how you split the test up so not always super reliable but it is cheaper because you only have to administer the test once
• IC: Cronbach's Alpha


  Cronbach's alpha is a statistic used to assess the internal consistency or reliability of a scale or questionnaire in industrial psychology. It measures the extent to which items within a scale measure the same underlying construct.

  
  

  A high Cronbach's alpha (typically above 0.7) indicates that the items in the scale are consistent and reliable in measuring the intended construct. Industrial psychologists use Cronbach's alpha to ensure that the measurement instruments they use in their research or assessments are reliable and valid.
• Inter-rater reliabilty


  different individuals make judgement about a person e.g ratings of performance of a worker made by several different supervisors

  Calculate various statistical indices to show level agreement among raters: Inter-rater reliability
• Methods of Estimating Reliability


  - test and retest

  - alternate forms

  - internal consistency

  - inter-rater reliability

  
  

  does the test measure what it claims to measure?
• The difference between validity and reliability

  Validity: relates to the measurement measuring what it claims to measure

  Reliability: relates to the consistency or stability of measurement
• Validity and Reliability


  Refers to whether the experiment was repeated to see if it yielded the same results each time. If so, the experiment is said to be "valid".

  
• Validity framework


  Conduct job analysis to identify the important demands of a job and the human attributes necessary to meet these demands
• job demands


  talk to people, convince people
• Job related attitudes


  friendly, assertive, persuasive
• job constructs


  extraversion
• predictors


  test scores
• criteria


  job performance
• Face validity


  how the test scores look:

  Validity approach that is demonstrated by the way the test looks in the 'eyes' of the test-takers
• face validity relevance


  makes test taking worthwhile, thereby increasing test taking motivation[& concomitantly makes for a reliable test taker and test taking]
• Is face validity a subjective/qualitative judgement?


  yes, It is a qualitative/ subjective judgement about whether the test items appear relevant for their purpose
• Criterion related validity


  demonstrated by correlating the test score with a performance measure; improves researcher's confidence in the inference

  
  

  that people with higher test scores have higher performance

  validity coefficient(correlation between a test score (predictor) and a performance measure(criterion)
• What are the two designs of criterion related validity?

  predictive validity

  concurrent validity
• Predictive validity


  heavily criticized ,not practical,

  -design in which there is a time lag between collection of the test data and the criterion data

  e.g test all applicants, then hire applicants without using test scores, go back over time and collect performance data
• Concurrent validity


  no lag, more realistic, by testing current employees rather than potential employees

  
  

  test taking motivation may not be as high for those already employed
• Content related validity


  demonstrates that the content of the selection procedure represents an adequate sample of important work behaviours and activities and/or worker KSAOs defined the job analyses
• KSAOs


  knowledge, skills and other attributes
• Steps and uses for content related validity


  ask subject matter experts

  analyse their answers to identify or develop possible predictors for testing them

  can be used to develop a test