reliability of selection measures
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Reliability of Selection Measures. Reliability Defined. The degree of dependability, consistency, or stability of scores on measures used in selection. Error of Measurement . Obtained Score True Score Error Score. Errors of Measurement.

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reliability defined
Reliability Defined

The degree of dependability,

consistency, or stability of

scores on measures used in


error of measurement
Error of Measurement

Obtained Score

  • True Score
  • Error Score
errors of measurement
Errors of Measurement

-Physical characteristics = Higher reliability (HR)

-Psychological attributes = Lower reliability (LR)


  • Large amounts of measurement

error = LR

  • Small amounts of measurement

Error = HR

methods of estimating reliability
Methods of Estimating Reliability
  • Examines two sets of measure
  • If scores from the two measurements are similar, reliability will be raised
  • If scores from the two measurements are dissimilar, reliability will be lowered
methods of estimating reliability6
Methods of Estimating Reliability
  • Statistical procedures calculated reliability coefficients range from 0.00 to 1.00
  • Higher the coefficient, the less the measurement error, and the higher the reliability estimate
  • Lower the coefficient, the higher the measurement error, and the lower the reliability estimate
methods of estimating reliability7
Methods of Estimating Reliability

Selecting a method:

  • Dependability of data collected today be reflective of the same person in the future
  • To what degree do evaluations vary from one another
  • Accuracy of scores on measuring the true ability
  • Dependability of an assessment of a measure at a given moment
methods of estimating reliability8
Methods of Estimating Reliability


Same measure is used to

collect data from the same

person at two different times

  • The higher the coefficient, the greater the approximation to the true score: closer to 1.00
  • The lower the coefficient, the greater likelihood of error: closer to .00
methods of estimating reliability9
Methods of Estimating Reliability

Test-Retest – Sources of error

  • Memory
  • Learning
  • “True change”
methods of estimating reliability10
Methods of Estimating Reliability

Parallel or Equivalent Forms

Does not use the same measure

twice but will instead use

equivalent versions of the measure

  • Each has same number of


  • Each has same level of difficulty
  • Averages of scores are the same
methods of estimating reliability11
Methods of Estimating Reliability

Internal Consistency Estimates

How similar are different parts of the measure (e.g. different questions on a test) in what they measure?

  • Split-half reliability
  • Kuder-Richardson Formula 20
  • Coefficient Alpha (α) – most commonly reported
factors influencing the reliability of a measure
Factors Influencing The Reliability of a Measure
  • Method of Estimating Reliability
  • Individual Differences Among Respondents
  • Length of a Measure
  • Test Question Difficulty
  • Administration of a measure
standard error of measurement
Standard Error of Measurement

Useful applications:

  • Forces us to think of scores on a measure not as exact points
  • Aid in decision making in which only one individual is involved
  • Determine the magnitude of how scores differ significantly from one another