Table 1
Descriptive statistics of #CDCGrandRounds and #VitalSigns.
| #CDCGrandrounds | #VitalSigns | ||
|---|---|---|---|
| Total number of original tweets in the corpus | 6,962 | * | 15,015 |
| Time Frame | August 18, 2011 to October 25, 2016 | March 19, 2013 to October 31, 2016 | |
| English tweets, n (%) | 6875 (98.75) | 13401 (89.25) | |
| Number of unique users | 1055 | 5154 | |
| Tweets with 0 URL links (%) | 4695 (67.44) | 5019 (33.43) | |
| Tweets with 1 URL links (%) | 2118 (30.42) | 8873 (59.09) | |
| Tweets with 2 URL links (%) | 146 (2.10) | 1113 (7.41) | |
| Tweets with 3 URL links (%) | 3 (0.04) | 10 (0.07) | |
| Number of cycles in the sample | 58 | 42 | |
| Number of original tweets per cycle, frequency† | |||
| Range | 6–349 | 151–1628 | |
| Median (Inter-quartile range) | 119 (75–157.5) | 256 (218.75–306.75) | |
| Mean (standard deviation) | 119.5172 (74.17056) | 368.125 (322.4237) | |
[i] *We excluded 4 #CDCGrandRounds tweets that were posted on April 21, 2011. These 4 tweets were not included in any of the cycles of the #CDCGrandRounds corpus. †For the frequency of the cycles of #VitalSigns, we excluded Cycle 1 and Cycle 42 here.
Table 2
Top 10 users (Twitter handles) and top 10 URL domains in the corpora of #CDCGrandRounds and #VitalSigns respectively.
| #CDCGrandRounds | N = 6,962 tweets | #VitalSigns | N = 15,015 tweets |
|---|---|---|---|
| Twitter handle | Frequency (%) | Twitter handle | Frequency (%) |
| @CDCgov | 1381 (19.8) | @RedneckJournal | 759 (5.05) |
| @CDC_eHealth | 882 (12.7) | @Pirate_Journal | 467 (3.11) |
| @CDCInjury | 349 (5.0) | @CDCgov | 389 (2.59) |
| @CDCChronic | 212 (3.0) | @CommFdnsCanada | 260 (1.73) |
| @MillionHeartsUS | 211 (3.0) | @DrFriedenCDC | 245 (1.63) |
| @CDC_Cancer | 138 (2.0) | @LdnCommFdn | 203 (1.35) |
| @DrFriedenCDC | 136 (2.0) | @HamCommFdn | 113 (0.75) |
| @CDCSTD | 135 (1.9) | @CDC_eHealth | 112 (0.75) |
| @CDC_NCBDDD | 126 (1.8) | @GoldenComFdn | 109 (0.73) |
| @CDC_HIVAIDS | 102 (1.5) | @Oxehealth | 90 (0.60) |
| #CDCGrandRounds | N = 2,419 URL links | #VitalSigns | N = 11,129 URL links |
| URL domain | Frequency (%) | URL domain | Frequency (%) |
| www.cdc.gov | 1424 (58.87) | Twitter.com | 2670 (23.99) |
| Twitter.com | 398 (16.45) | www.cdc.gov | 2058 (18.49) |
| www.youtube.com | 160 (6.61) | www.redneckjournal.com | 658 (5.91) |
| Storify.com | 34 (1.41) | www.piratejournal.com | 467 (4.20) |
| www.onlinevideoservice.com | 25 (1.03) | www.instagram.com | 416 (3.74) |
| Wm.onlinevideoservice.com | 21 (0.87) | www.youtube.com | 319 (2.87) |
| Paper.li | 18 (0.74) | www.vitalsignscanada.ca | 157 (1.41) |
| www.facebook.com | 12 (0.50) | www.facebook.com | 133 (1.20) |
| Millionhearts.hhs.gov | 10 (0.41) | www.whizart.com | 130 (1.17) |
| www.hhs.gov | 9 (0.37) | Soundcloud.com | 102 (0.92) |
| URL links not resolved | 54 (2.23) | URL links not resolved | 406 (3.65) |
Table 3
Prevalence ratio of retweet frequency in the corpora of #CDCGrandRounds and #VitalSigns tweets for predictor variables in univariable and multivariable negative binomial regression models.
| Univariable regression | Multivariable regression | |||
|---|---|---|---|---|
| Prevalence ratio (95% CI) | P-value | Prevalence ratio (95% CI) | P-value | |
| #CDCGrandRounds | ||||
| Hashtag count | 0.8208 (0.7790, 0.8657) | <0.001 | 1.0784 (1.0302, 1.1292) | <0.001 |
| Mention count | 0.6673 (0.6271, 0.7105) | <0.001 | 0.8613 (0.8152, 0.9100) | <0.001 |
| URL link count | 1.7273 (1.6045, 1.8608) | <0.001 | 1.7773 (1.6729, 1.8890) | <0.001 |
| Log(follower count)* | 1.3876 (1.3709, 1.4045) | <0.001 | 1.4332 (1.4111, 1.4557) | <0.001 |
| Log(friend count)* | 0.7996 (0.7711, 0.8296) | <0.001 | 0.9082 (0.8755, 0.9422) | <0.001 |
| Log(status count)* | 1.5522 (1.4939, 1.6130) | <0.001 | 0.8538 (0.8213, 0.8878) | <0.001 |
| Log(favorite count)* | 0.9424 (0.9214, 0.9637) | <0.001 | 1.0805 (1.0579, 1.1035) | <0.001 |
| #VitalSigns | ||||
| Hashtag count | 0.6866 (0.6654, 0.7085) | <0.001 | 0.9688 (0.9472, 0.9908) | 0.005 |
| Mention count | 0.7411 (0.7114, 0.7726) | <0.001 | 1.1748 (1.1404, 1.2104) | <0.001 |
| URL link count | 3.7244 (3.4586, 4.0113) | <0.001 | 1.2155 (1.1587, 1.2752) | <0.001 |
| Log(follower count)* | 1.7855 (1.7642, 1.8073) | <0.001 | 2.0256 (1.9957, 2.0563) | <0.001 |
| Log(friend count)* | 0.8634 (0.8309, 0.8975) | <0.001 | 0.8583 (0.8376, 0.8795) | <0.001 |
| Log(status count)* | 1.1712 (1.1324, 1.2106) | <0.001 | 0.6579 (0.6441, 0.6719) | <0.001 |
| Log(favorite count)* | 1.1475 (1.1188, 1.1766) | <0.001 | 1.1205 (1.1043, 1.1370) | <0.001 |
[i] *To perform the logarithmic transformation, the frequency of follower count, friend counts, status count and favorite count were added 0.5 respectively to avoid the situation of having log(0). CI, confidence interval.
Figure 1
Prevalence ratio (PR, with 95% confidence intervals) of the effect of attaching a photo or video on retweet count for #VitalSigns over different cycles.