Table 2.
Item parameters and item-fit at wave 1.
| Location parameter (b) | Discrimination parameter (a) | Item-fit | ||||||
|---|---|---|---|---|---|---|---|---|
| Value | Std. Err. | Z-value | Value | Std. Err. | Z-value | p-value | ||
| 1 | Facial expressions | 2.09 | 0.05 | 43.95 | 1.76 | 0.07 | 26.64 | .089 |
| 2 | Eye contact | 1.56 | 0.02 | 69.29 | 3.51 | 0.15 | 23.04 | .614 |
| 3 | General level of activity | 3.29 | 0.14 | 23.19 | 1.11 | 0.06 | 18.12 | .020 |
| 4 | Self-stimulating gestures | 4.42 | 0.36 | 12.21 | 1.29 | 0.14 | 9.49 | .624 |
| 5 | Vocalizations | 1.71 | 0.04 | 38.43 | 1.22 | 0.04 | 28.95 | .614 |
| 6 | Briskness of response to stimulation | 3.19 | 0.13 | 23.74 | 1.78 | 0.12 | 15.03 | .901 |
| 7 | Relationship | 1.35 | 0.01 | 185.37 | 12.14 | 3.85 | 3.16 | .010 |
| 8 | Attraction | 1.33 | 0.01 | 95.30 | 4.56 | 0.22 | 20.86 | .168 |