N=51 (M=25, F=26) mean age=47.2yrs; mean education years=11.2yrs; mean age of onset=24.8yrs; range of CGIS=1-4
1. Test-retest reliability, random measurement error and practice effect:
Low load indices: good
High load indices: need to be improved due to substantial random measurement error and moderate practice effect
Indices
|
ICC
(95% CI)
|
SEM
(SEM%)
|
MDC
(MDC%)
|
Effect
size
(s: significant; ns: not significant)
|
Low load (L)
|
0.89
(0.80-0.94)
|
0.11
(9.5%)
|
0.29
(26.3%)
|
0.14
(s)
|
Low load with Distractor (LD)
|
0.88 (0.78-0.93)
|
0.12
(10.8%)
|
0.35
(29.8%)
|
0.15
(s)
|
High load (H)
|
0.75 (0.33-0.89)
|
0.40
(14.6%)
|
1.11
(40.5%)
|
0.43
(s)
|
High load with Distractor (HD)
|
0.74 (0.41-0.87)
|
0.47
(16.8%)
|
1.31
(46.4%)
|
0.39
(s)
|
(1) The ICC for the L and LD indices ranged from 0.88 to 0.89, indicating that both low load indices had high test-retest reliability.
(2) The ICC for the H and HD indices ranged from 0.74 to 0.75, indicating that both high load indices had acceptable test-retest reliability.
(3) Our results showed that both low load indices had acceptable random measurement error, whereas both high load indices had substantial random measurement error.
*The criterion for the MDC% was set at 30%. MDC%<30% indicates acceptable random measurement error.
(4) A significant practice effect was shown between repeated assessments for all four indices. For both low load indices, the practice effect was negligible; whereas for both high load indices, the practice effect was around moderate.
2. Convergent validity
(1) Correlation with MoCA: acceptable
L
|
LD
|
H
|
HD
|
0.42
|
0.43
|
0.48
|
0.47
|
| All four indices had fair correlations with the MoCA, indicating acceptable convergent validity. (2) Correlation with CGIS: insufficient Only the L and LD indices had weak correlations (r=0.28-0.29) with the CGIS, indicating insufficient convergent validity.
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