TABLE 1—
Frequency of Use of Different Metadata Elements That Can Be Extracted From Twitter in Included Articles: 2010–2015
| Data | Articles, No. (%) |
| Explicit data about user | |
| Twitter handle | 6 (4) |
| Language | 0 (0) |
| Time zone | 4 (3) |
| Location | 12 (9) |
| Date account created | 5 (4) |
| User profile (free text) | 5 (4) |
| User profile photo | 2 (1) |
| Total number of tweets | 11 (8) |
| Number of followers | 26 (19) |
| Number following | 6 (4) |
| Extractable data about user | |
| Age | 1 (1) |
| Gender | 5 (4) |
| Marital status | 1 (1) |
| Political party | 0 (0) |
| Race/ethnicity | 1 (1) |
| Occupation | 5 (4) |
| Interests | 0 (0) |
| Religion | 0 (0) |
| Income | 1 (1) |
| Mood | 1 (1) |
| Disease state | 5 (4) |
| Network | 5 (4) |
| Explicit data from tweet | |
| 140 characters | 112 (82) |
| #hashtag | 13 (9) |
| URL | 6 (4) |
| Geotag | 28 (20) |
| Application used to send tweet | 2 (1) |
| Number of retweets | 12 (9) |
| Number of favorites | 1 (1) |
| Linked images | 2 (1) |
| User mentions | 3 (2) |
| Time and date of tweet | 19 (14) |
| Extractable data about tweet | |
| Content | 77 (55) |
| Sentiment | 21 (15) |
| Image analysis | 1 (1) |
| Language | 4 (3) |
Note. URL = uniform resource locator.