Table 6 Internal consistency and test–retest reliability
Scale | Sub-Group | Validation sample | Cross-validation sample | ||||||
|---|---|---|---|---|---|---|---|---|---|
Test–retest reliability | Internal consistency reliability | Test–retest reliability | Internal consistency reliability | ||||||
n | ICC (p) | n | α | n | ICC (p) | n | α | ||
ITT | Full sample | 279 | .886 (< .001) | 1495 | .958 | 283 | .930 (< .001) | 1448 | .962 |
ASPQ | 48 | .790 (< .001) | 260 | .938 | 53 | .806 (< .001) | 248 | .953 | |
ASNPQ | 58 | .745 (< .001) | 333 | .923 | 49 | .929 (< .001) | 315 | .922 | |
EV Users | 54 | .650 (< .001) | 277 | .876 | 50 | .885 (< .001) | 283 | .899 | |
Former Users | 57 | .672 (< .001) | 302 | .948 | 61 | .893 (< .001) | 275 | .957 | |
Never Users | 62 | .858 (< .001) | 323 | .945 | 70 | .861 (< .001) | 327 | .950 | |
ITU | Full sample | 279 | .886 (< .001) | 1495 | .973 | 283 | .911 (< .001) | 1448 | .973 |
ASPQ | 48 | .838 (< .001) | 260 | .968 | 53 | .781 (< .001) | 248 | .966 | |
ASNPQ | 58 | .761 (< .001) | 333 | .946 | 49 | .910 (< .001) | 315 | .939 | |
EV Users | 54 | .796 (< .001) | 277 | .935 | 50 | .862 (< .001) | 283 | .952 | |
Former Users | 57 | .715 (< .001) | 302 | .972 | 61 | .816 (< .001) | 275 | .983 | |
Never Users | 62 | .741 (< .001) | 323 | .985 | 70 | .908 (< .001) | 327 | .978 | |
ITDU | Full sample | 115 | .759 (< .001) | – | – | 109 | .798 (< .001) | – | – |
ASPQ | 42 | .817 (< .001) | – | – | 46 | .721 (< .001) | – | – | |
ASNPQ | 49 | .742 (< .001) | – | – | 39 | .684 (< .001) | – | – | |
EV Usersa | 24 | .395 (.026) | – | – | 24 | .755 (< .001) | – | – | |
ITS | Full sample | 115 | .813 (< .001) | 742 | .965 | 109 | .834 (< .001) | 701 | .973 |
ASPQ | 42 | .858 (< .001) | 260 | .972 | 46 | .746 (< .001) | 248 | .978 | |
ASNPQ | 49 | .687 (< .001) | 333 | .964 | 39 | .880 (< .001) | 315 | .963 | |
EV Users | 24 | .739 (< .001) | 149 | .920 | 24 | .857 (< .001) | 138 | .964 | |