Table 2.

Types of social media studied (N = 43^*)

Social media	N	Studies
Twitter	16	Biswas,3 Chew and Eysenbach,14 Collier et al,15 Ding and Zhang,16 Freberg et al,9 Gaspar et al,39 Househ,27 Kim and Liu,18 Lazard et al,28 Liu and Kim,19 Mollema et al,40 Odlum and Yoon,30 Signorini et al,23 Towers et al,34 Vos and Buckner,37 Wong et al35
YouTube	6	Basch et al,26 Ding and Zhang,16 Dubey et al,38 Nagpal et al,29 Pandey et al,22 Pathak et al31
Facebook	6	Biswas,3 Ding and Zhang,16 Kim and Liu,18 Liu and Kim,19 Mollema et al,40 Strekalova33
Blogs	6	Ding and Zhang,16 Freberg et al,9 Gao et al,17 Mollema et al,40 Nerlich and Koteyko,21 Tausczik et al24
Discussion forums	3	Luoma-aho et al20 Mollema et al,40 Tirkkonen and Luoma-aho25
Flickr	2	Ding and Zhang,16 Seltzer et al32
Instagram	1	Seltzer et al32
Web site comments	1	Atlani-Duault et al13
Weibo	1	Fung et al36
Delicious	1	Freberg et al9

^*The total number is >30 because many articles studied multiple social media outlets.