TABLE 1—

Descriptive Characteristics of Analytical Sample of Facebook Posts, Advocacy Organizations, Social Media Users, and Broader External Factors That Shape Social Media Virality: July 19, 2011–December 18, 2012

Characteristic	Mean (SD)	Min	Max
Post-level indicators
Viral views	31.05 (176.42)	0.00	6 749
No. unique people who made emotional comments about post	0.25 (1.05)	0.00	36
Emotional language, %
All	5.86 (6.65)	0.00	100
Positive	5.25 (6.45)	0.00	100
Negative	0.58 (2.09)	0.00	33
Contains audiovisual	0.20 (0.40)	0.00	1
Novel words in post, %	0.12 (0.16)	0.00	100
Emotional language in comments about post, %
All	3.46 (10.02)	0.00	100
Positive	3.24 (9.88)	0.00	100
Negative	0.21 (1.25)	0.00	33
No. people who commented on post	0.78 (2.49)	0.00	55
Organization-level indicators
No. Facebook fans	1 546.73 (2 772.00)	33.00	17 952
No. volunteers or members	454.11 (2 314.60)	0.15	17 136
Total year-end budget, US$	1 644 508.00 (4 813 029.00)	0.00	35 569 996
Age, y	10.17 (12.97)	1.00	88
No. views from Facebook post advertising	46.98 (2 621.53)	0.00	212 422
No. posts during previous week	0.70 (0.50)	0.08	2
Audience-level indicators
Female post viewers, %	0.70 (0.11)	0.15	1
Post viewers younger than 35 y, %	0.46 (0.19)	0.05	100
No. post viewers by US region
New England	348.78 (1 109.35)	0.00	11 857
Middle Atlantic	1 141.59 (2 460.70)	0.00	33 248
East Central	826.20 (1 474.46)	0.00	12 903
West North Central	130.59 (390.33)	0.00	5 739
South Atlantic	26.64 (132.15)	0.00	3 327
West South Central	564.61 (907.86)	0.00	8 526
No. post viewers outside US	27.39 (33.42)	0.00	130
Broader external indicators
No. news articles about organization	0.01 (0.05)	0.00	2
No. blog mentions about organization	0.13 (0.42)	0.00	7
Google autism search index	35.02 (9.53)	13.00	95

Note. Table shows data of 7366 Facebook posts produced by 47 advocacy organizations.