Psychological Assessment - Reliability

Psychometric Reliability →



Reliability Coefficient
SOURCES OF ERROR VARIANCE
Item Sampling or Content Sampling
The Concept of Reliability
➢
→
Error content sampled
the way the content is sampled
𝑿=𝑻+𝑬
Where
→

Variance (𝜎 2 ) Test Administration




𝝈𝟐 = 𝝈𝟐𝒕𝒉 + 𝝈𝟐𝒆 → Testtaker Variables
Where 𝝈 𝟐

𝝈𝟐𝒕𝒉 𝝈𝟐𝒆

Reliability → Examiner-Related Variables


→  

Test Scoring and Interpretation
→

→ Scorer (or Rater)

Measurement Error

Sampling Error
Random Error



→
Methodological Error


Systematic Error



→

, Reliability Estimates Parallel Forms

TEST-RETEST RELIABILITY ESTIMATES
Test-Retest Method or Time Sampling →



→
Test-Retest Reliability
→ Parallel Forms Reliability



→
Alternate Forms

→
→


→ Alternate Forms Reliability

Coefficient of Stability


➢
➢
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→ Carryover Effects ➢



→ Practice Effects ➢




INTERNAL CONSISTENCY ESTIMATE OF RELIABILITY

Internal Consistency Estimate of Reliability or Estimate of
PARALLEL-FORMS & ALTERNATE-FORMS RELIABILITY
Inter-Item Consistency
ESTIMATES

Coefficient of Equivalence


Inter-Item Consistency

→
➢
equivalent forms reliability