Read the summary and the most important questions on Modern Psychometrics, Third Edition The Science of Psychological Assessment | 9781317723776 | John Rust; Susan Golombok

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• Two obstacles for the development of tests

  • Differences were seen as experimental flaws
  • More basic functions (such as vision) were tested

• Three fields initiated development of tests

  • Psychiatry: Was in need to diagnose mental disorders
  • Experimental psychology: Was in need of standardisation
  • Genetics: Wanted to research individual differences

• Degeneration hypothesis (central to eugenics)

  Central to eugenics is the degeneration hypothesis. A population is said to be degenerating (dysgenic) if it exhibits either enhanced reproduction levels among organisms with seemingly undesirable characteristics, or if it exhibits diminished reproduction among organisms with seemingly desirable characteristics. 

• biometrical genetics (known from twin studies)

  Biometrical approach deals not with absolute (as Mendelian approach does) but with variation in a trait. The more equal changes between people are, the more is relied on genes. It is found that almost all psychological characteristics that we can reliably measure have a genetic and environmental component (each accounting for about half of the variance).

• Eysenck (neuropsychological) approach of intelligence

  Eysenck carried out experiments to attempt to relate scores on IQ tests directly to brain functioning. The Eysenck approach is based on the belief in the possibility of a direct relationship between a person's intellectual ability and the speed at which the neurons within the brain actually transmit nerve signals.

• It is also problematic that in society the term ‘intelligence’ is already heavily loaded with meaning. Once these problems with the way the concept of intelligence was being used were recognised, several strategies were developed to overcome them. Name two:

  • The word ‘intelligence’ was replaced for ‘ability’ in existing tests.
  • Attention focused increasingly on what a person with high ability was actually able to do 

• The fundamental equation for classical test theory is

  X = T + E
  
  X is the observed sum score
  T is the true score (the latent trait you want to measure)
  E is the random error

• Assumptions of the classical test theory

  1. The errors cancel out if you make multiple tests
  2. The error is unrelated to the true score

• Advantages of objective tests over open-ended tests

  1. Reliability of scoring is higher
  2. Easier to identify strengths and weaknesses
  3. Takes longer to construct, but is easier to mark

• Formula for the correction for guessing

  C = R - (W / (N-1))
  
  C = corrected score
  R = number of correct items
  W = number of incorrect items
  N = number of alternatives or response options     
  
  The formula underestimates the amount of guessing.