Are Your Tests Reliable? 4 Types of Reliability YouTube Lecture Handouts

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Are Your Tests Reliable? 4 Types of Reliability
Types of Reliability

Test – Retest Reliability

Test - Retest Reliability
Table of Student Data for Test a Reliability
Student IDExam scoreRepeat score (same exam)
14549
25860
33241
45458
54854

Parallel or Alternate Form Reliability

Table of Student Data for Parallel or Alternate Form Reliability
Student IDExam A scoreExam B score
15758
25456
34145
43241
55857

Inter-Rater Reliability or Inter-Observer Reliability or Inter-Coder Reliability

Object or Phenomenon
  • Consensus in observations among different people (assuming observation are the same)
  • Degree of scoring stability a measure yields across multiple observers
  • Measure of agreement among raters
  • Improving Rater Reliability – Training/Guided Revisions

What Affects Inter-Rater Reliability?

  • Halo Effect (one dimension influencing others)
  • Stereotyping (impressions on group may influence individual)
  • Perception Differences (rater viewpoints and past experiences)
  • Leniency/Stringency Error (lack of knowledge)

Internal Consistency Reliability

Internal Consistency Reliability

  • Extent to which the items of a measure assess a common characteristic
  • Single measurement instrument administered to a group on one occasion
  • Estimate how well items that reflect the same construct yield similar results
  • How consistent the results are for different items for the same construct within the measure

Average Inter-Item Correlation

Average Inter-Item Correlation

Average Item Total Correlation

Average Item Total Correlation

Split Half Reliability Spearman – Brown prediction formula

Split Half Reliability
Table of Student Data for Split Half Reliability
Student IDScore on even itemsScore on odd items
12324
23029
32625
41920
52423

Cronbach Alpha (α) Average of all possible split-half correlations

Average of All Possible Split - Half Correlations

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