Table 2.
The 3×50 contingency table.
| Words and phrases | Period 1 frequency, n (%) | Period 2 frequency, n (%) | Period 3 frequency, n (%) |
| e-cigarettea | 3308 (4.30) | 13015 (4.96) | 6266 (5.65) |
| cigarette | 821 (1.07) | 4101 (1.56) | 1449 (1.31) |
| nicotine | 1185 (1.54) | 2933 (1.12) | 740 (0.67) |
| harm | 693 (0.90) | 2942 (1.12) | 772 (0.70) |
| smoking | 803 (1.04) | 2532 (0.96) | 701 (0.63) |
| smoking cessation | 812 (1.05) | 2692 (1.03) | 348 (0.31) |
| tobacco | 460 (0.60) | 1837 (0.70) | 1098 (0.99) |
| tar | 912 (1.18) | 1466 (0.56) | 575 (0.52) |
| problem | 292 (0.38) | 1181 (0.45) | 626 (0.56) |
| product | 297 (0.39) | 1017 (0.39) | 618 (0.56) |
| health | 298 (0.39) | 1119 (0.43) | 466 (0.42) |
| country | 116 (0.15) | 864 (0.33) | 690 (0.62) |
| market | 198 (0.26) | 711 (0.27) | 576 (0.52) |
| use | 352 (0.46) | 861 (0.33) | 232 (0.21) |
| smoker | 201 (0.26) | 801 (0.31) | 327 (0.29) |
| taste | 344 (0.45) | 656 (0.25) | 255 (0.23) |
| industry | 0 (0.00) | 569 (0.22) | 616 (0.56) |
| brand | 136 (0.18) | 491 (0.19) | 594 (0.54) |
| smog | 348 (0.45) | 665 (0.25) | 0 (0.00) |
| tradition | 143 (0.19) | 621 (0.24) | 301 (0.27) |
| America | 0 (0.00) | 616 (0.23) | 303 (0.27) |
| forbid | 124 (0.16) | 438 (0.17) | 457 (0.41) |
| cartridge | 130 (0.17) | 458 (0.17) | 402 (0.36) |
| tar | 167 (0.22) | 654 (0.25) | 0 (0.00) |
| influence | 167 (0.22) | 537 (0.20) | 246 (0.22) |
| sale | 0 (0.00) | 0 (0.00) | 601 (0.54) |
| produce | 193 (0.25) | 633 (0.24) | 193 (0.17) |
| China | 0 (0.00) | 515 (0.20) | 294 (0.27) |
| low voltage e-cigarette | 172 (0.22) | 519 (0.20) | 0 (0.00) |
| body | 166 (0.22) | 532 (0.20) | 0 (0.00) |
| choice | 162 (0.21) | 444 (0.17) | 201 (0.18) |
| channel | 0 (0.00) | 0 (0.00) | 624 (0.56) |
| minor | 0 (0.00) | 0 (0.00) | 562 (0.51) |
| component | 150 (0.19) | 489 (0.19) | 0 (0.00) |
| content | 159 (0.21) | 461 (0.18) | 0 (0.00) |
| burn | 137 (0.18) | 527 (0.20) | 0 (0.00) |
| research | 153 (0.20) | 523 (0.20) | 0 (0.00) |
| flavor | 176 (0.23) | 326 (0.12) | 241 (0.22) |
| atomize | 133 (0.17) | 479 (0.18) | 0 (0.00) |
| company | 0 (0.00) | 408 (0.16) | 238 (0.21) |
| supervise | 0 (0.00) | 343 (0.13) | 325 (0.29) |
| user | 0 (0.00) | 371 (0.14) | 235 (0.21) |
| addiction | 0 (0.00) | 406 (0.15) | 0 (0.00) |
| heat | 0 (0.00) | 465 (0.18) | 0 (0.00) |
| offline | 0 (0.00) | 0 (0.00) | 600 (0.54) |
| advice | 129 (0.17) | 0 (0.00) | 175 (0.16) |
| friends | 110 (0.14) | 327 (0.12) | 0 (0.00) |
| data | 0 (0.00) | 387 (0.15) | 0 (0.00) |
| atomizer | 172 (0.22) | 0 (0.00) | 0 (0.00) |
| teenager | 0 (0.00) | 0 (0.00) | 177 (0.16) |
| sum | 76,976 (14.32) | 26,2491 (19.8) | 11,0895 (20.85) |
ae-cigarette: electronic cigarette.