Table 3.
Usability: factor reliabilities, factor median, and the impact of these factors on effect size (low versus high, Q-model and P value for difference) among 12 interventions.
| Scale | α | Median of scale | ḡ (95% CI) | Between groups Q (P value) | |
| Low (≤median of scale) | High (>median of scale) |
|
|||
| Learnabilitya | .52b | - | - | - | - |
| Efficiency | .69 | 3.33 | 0.02 (-0.29 to 0.10) | 0.43 (0.18-0.67) | 4.25 (.04) |
| Memorability | .91 | 5.00 | 0.32 (-0.23 to 0.87) | 0.22 (-0.09 to 0.53) | 0.09 (.76) |
| Errorsc | .70 | 3.33 | 0.47 (0.31-0.63) | 0.15 (-0.34 to 0.64) | 1.45 (.23) |
| Satisfactiond | .73 | 4.00 | 0.37 (0.01-0.73) | 0.15 (-0.22 to 0.53) | 0.67 (.41) |
| Personalizatione | .70 | 2.33 | 0.15 (-0.19 to 0.49) | 0.38 (0.05-0.68) | 0.82 (.37) |
| Situatedness | .98 | 2.00 | 0.21 (-0.08 to 0.50) | 0.52 (0.23-0.81) | 2.14 (.14) |
| Social Interaction | .94 | 3.33 | 0.10 (-0.40 to 0.69) | 0.34 (0.04-0.65) | 0.68 (.41) |
aItem 4 removed from scale.
bScale not analyzed because of low reliability.
cItem 10 removed from scale.
dItem 16 removed from scale.
eItem 21 removed from scale.