Please enable JavaScript.
Coggle requires JavaScript to display documents.
Reliability: Theoretical Basis (Wk 3) (Classical Test Theory (CTT) (CTT in…
Reliability: Theoretical Basis (Wk 3)
Classical Test Theory (CTT)
Four Conceptions of Reliability
Standard Error of Measurement
Types of Scores in CTT:
Observed score / True score / Error score variability
Parallel Test
CTT in General
Function
Outlines procedures for estimating reliability of psychological measures
Assumption
Reliability is the degree in differences with observed scores that are consistent with differences in their true scores.
Definition
A measurement theory that defines reliability (using theoretical basis)
Definition of Reliability
Not an all-or-nothing
thing (Reliable / Not Reliable) :green_cross:
Consistency of Measurement
Exists on a
Continuum
(More Reliable / Less Reliable ):check:
Measurement Error cannot be fully omitted, so scores can be unreliable to some degree.
Types of Scores in CTT
Measurement Error (ME)
Creates inconsistency between observed + true scores
Source of ME
Test Construction
Test Administration
Test Scoring and Interpretation
Component of observed score > nothing to do with psychological characteristic that is being measured
ME is random: likely to inflate / deflate the score
Error cancel itself out across respondants
Error scores are uncorrelated with true scores
Observed Score
True score + measurement error = Observed Score
The only amount / score we know when testing (as it's contaminated by ME)
True Score
Actual amount of psychological characteristics being measured that the respondent possesses
Variance in Scores
Depends on the link between observed, true & error score
FORMULA: Relationship of the 3 variances (squared)
The need for consistency between (true & observed score) differences
Four Conceptions of Reliability
Terminology