Reliability
Measurement
error
1.
Systematic
error
2.
Random
error
True score
X=T+E
|
where |
T
True score |
|
|
E Random error |
|
|
X Observed score |
|
Assumptions behind CTT |
|
|
Repeated measurement design for 1 individual |
Measuring more than 1 individual |
|
X=T+E |
X=T+E |
|
Normal distribution of observed score for that
individual μX=T |
μE=0 (Normal distribution) μX=μT |
|
Distribution
of X and E are the same |
|
|
|
|
|
|
Properties useful to develop the reliability
coefficient |
Estimating
the reliability coefficient
1.
2.
Derive the
correlation between the observed and true score
Derive the
correlation between // test forms
