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 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


Error of Measurement

Obtained Score

  • True Score

  • Error Score

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

  • 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 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 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 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 Reliability

Test-Retest – Sources of error

  • Memory

  • Learning

  • “True change”

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 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

  • Method of Estimating Reliability

  • Individual Differences Among Respondents

  • Length of a Measure

  • Test Question Difficulty

  • Administration of a measure

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

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