Table 1. Content Validity Index of SAS.
| Items | Number in Experts' Agreement | Item CVI | |
| 1 | Missing planned work due to smartphone use | 7 | 1.000 |
| 2 | Having a hard time concentrating in class, while doing assignments, or while working due to smartphone use | 7 | 1.000 |
| 3 | Experiencing lightheadedness or blurred vision due to excessive smartphone use | 5 | .714 |
| 4 | Feeling pain in the wrists or at the back of the neck while using a smartphone | 6 | .857 |
| 5 | Feeling tired and lacking adequate sleep due to excessive smartphone use | 4 | .571 |
| 6 | Feeling calm or cozy while using a smartphone | 1 | .143 |
| 7 | Feeling pleasant or excited while using a smartphone | 4 | .571 |
| 8 | Feeling confident while using a smartphone | 3 | .429 |
| 9 | Being able to get rid of stress with a smartphone | 3 | .429 |
| 10 | There is nothing more fun to do than using my smartphone. | 3 | .429 |
| 11 | My life would be empty without my smartphone. | 4 | .571 |
| 12 | Feeling most liberal while using a smartphone | 0 | .000 |
| 13 | Using a smartphone is the most fun thing to do. | 5 | .714 |
| 14 | Won't be able to stand not having a smartphone | 7 | 1.000 |
| 15 | Feeling impatient and fretful when I am not holding my smartphone | 7 | 1.000 |
| 16 | Having my smartphone in my mind even when I am not using it | 7 | 1.000 |
| 17 | I will never give up using my smartphone even when my daily life is already greatly affected by it | 6 | .857 |
| 18 | Getting irritated when bothered while using my smartphone | 5 | .714 |
| 19 | Bringing my smartphone to the toilet even when I am in a hurry to get there | 4 | .571 |
| 20 | Feeling great meeting more people via smartphone use | 2 | .286 |
| 21 | Feeling that my relationships with my smartphone buddies are more intimate than my relationships with my real-life friends | 5 | .714 |
| 22 | Not being able to use my smartphone would be as painful as losing a friend. | 4 | .571 |
| 23 | Feeling that my smartphone buddies understand me better than my real-life friends | 3 | .429 |
| 24 | Constantly checking my smartphone so as not to miss conversations between other people on Twitter or Facebook | 6 | .857 |
| 25 | Checking SNS (Social Networking Service) sites like Twitter or Facebook right after waking up | 5 | .714 |
| 26 | Preferring talking with my smartphone buddies to hanging out with my real-life friends or with the other members of my family | 3 | .429 |
| 27 | Preferring searching from my smartphone to asking other people | 1 | .143 |
| 28 | My fully charged battery does not last for one whole day. | 2 | .286 |
| 29 | Using my smartphone longer than I had intended | 7 | 1.000 |
| 30 | Feeling the urge to use my smartphone again right after I stopped using it | 4 | .571 |
| 31 | Having tried time and again to shorten my smartphone use time, but failing all the time | 5 | .714 |
| 32 | Always thinking that I should shorten my smartphone use time | 4 | .571 |
| 33 | The people around me tell me that I use my smartphone too much | 6 | .857 |
| Mean I-CVI | .943 | ||
| S-CVI/UA | .600 |
I-CVI, item-level content validity index.
S-CVI/UA, scale-level content validity index, universal agreement calculation method.