TABLE 2—
Manual Annotation and Topic Labels by Theme: Twitter, 2014–2017
| Broad Theme | Manual Annotation, No. (%) | LDA Topics, No. (%) | Pa |
| Antivaccine | 2241 | 28 | .03 |
| Alternative medicine | 50 (2) | 0 (0) | |
| Civil liberties | 248 (11) | 5 (18) | |
| Conspiracy | 903 (40) | 11 (39) | |
| Morality | 105 (5) | 0 (0) | |
| Safety concerns | 1322 (59) | 12 (43) | |
| Provaccine | 1744 | 48 | .24 |
| Pro-science | 85 (5) | 4 (8) | |
| Provaccine policy | 92 (5) | 5 (10) | |
| Criticizing antivaccine | 538 (31) | 13 (27) | |
| Promotion | 648 (37) | 11 (23) | |
| Safety and effectiveness | 523 (30) | 15 (31) | |
| Neutral | 6015 | 33 |
Note. LDA = latent Dirichlet allocation.
a
Fisher exact test or χ2.