Table 4.
Test-retest reliability and practice effects (significant t values in italics) for the Amsterdam Cognition Scale (Total participants [N]=248). ICC: intraclass correlation coefficient; N/A: not applicable; SDC: smallest detectable change; SEM: standard error of measurement.
| Test | n (%) | Mean 1 (SD) | Mean 2 (SD) | t value (degrees of freedom), P value | SEM | SDC groupa,b | ICCc | Correlation coefficientc | Literatured | |
| Connect the Dots I | 240 (96.8) | 34.83 (9.39) | 32.48 (7.79) | 5.43 (239), <.001 | 4.76 | 1.00 | .67 | .75e | .55-.73 | |
| Connect the Dots II | 246 (99.2) | 58.05 (18.45) | 54.95 (17.62) | 3.6 (245), <.001 | 9.55 | 1.89 | .71 | .74e | .56-.79 | |
| Wordlist Learning | 241 (97.2) | 52.02 (10.13) | 58.11 (9.80) | −12.31 (240), <.001 | 5.44 | 1.36 | .59 | .75e | .80 | |
| Wordlist Delayed recall | 241 (97.2) | 11.15 (2.71) | 12.09 (2.88) | −5.34 (240), <.001 | 3.69 | 0.72 | .50 | .64e | .83 | |
| Wordlist Recognition | 242 (97.6) | 44.17 (1.57) | 44.31 (1.72) | −1.76 (241), .08 | 0.90 | 0.16 | .70 | .54e | .48 | |
| Reaction Speed | 241 (97.2) | 308.88 (44.57) | 310.49 (44.85) | −0.69 (240), .49 | 25.60 | 4.60 | .67 | .74e | .20-.82 | |
| Place the Beadsf | 143 (100) | 25.63 (14.03) | 21.54 (15.81) | 3.17 (142), .002 | 11.15 | 2.93 | .45 | .50e | .38-.70 | |
| Box Tapping | 232 (93.5) | 9.17 (2.26) | 9.70 (1.91) | −3.91 (231), <.001 | 1.47 | 0.30 | .49 | .46e | .42-.79 | |
| Fill the Grid | 241 (97.2) | 62.59 (12.69) | 60.73 (11.42) | 3.85 (240), <.001 | 5.30 | 0.95 | .80 | .81e | .72-.86 | |
| Digit Sequences I | 245 (98.8) | 10.40 (2.22) | 10.61 (2.17) | −1.52 (244), .13 | 1.49 | 0.28 | .54 | .54g | .61-.78 | |
| Digit Sequences II | 242 (97.6) | 8.50 (2.72) | 8.78 (2.87) | −1.81 (241), .07 | 1.68 | 0.32 | .64 | .64g | .46-.71 | |
| Total scoreh | 206 (83.1) | 0.06 (.53) | 0.07(.55) | −0.23 (205), .82 | 0.05 | 0.01 | .83 | .83g | N/A |
|
aSDC group: SDC / √n.
bFor measures with a significant practice effect (t value in italics), Mean1 – Mean2 difference scores were added.
cAll correlation coefficients were significant at P<.001.
dRange of Pearson r correlation coefficients as found in the literature on studies with retest intervals between 2 weeks and 6 months on adults without progressive disease is presented: Trail Making Test A [51-54]; Trail Making Test B [23,53,54]; 15 Word Test Learning and Delayed Recall [50]; 15 Word Test Recognition [55]; Visual Reaction Time FePsy [55,56]; Tower of London [23,56-58]; Corsi Block-tapping [52,57,59,60]; Grooved Pegboard [61,62]; WAIS Digit Span [36,63].
eSpearman ρ.
fAnalyses performed on data from the Place the Beads sample; participants that completed both assessments only (n=143).
gPearson r.
hTotal score is based on mean standardized scores from Connect the Dots I and II, Wordlist Learning and Delayed Recall, Reaction Speed, Box Tapping, Fill the Grid, and Digit Sequences I and II.