Table 3.

Institutions Engaged in Acupuncture for Migraine That Details of Knowledge Clusters

Cluster ID	Size	Silhouette	Mean (Year)	Label (LLR)	Label (MI)
0	14	0.954	2007	Migraine prophylaxis	Placebo effect
1	13	0.865	2015	Chronic pain	Placebo effect
2	12	0.954	2012	Controlled trial	Placebo effect
3	11	0.848	2012	Pet-ct study	Placebo effect
4	10	0.936	2012	Altered periaqueductal gray resting state	Clinical trial
7	7	0.976	2012	Herbal formula granule	Clinical trial
8	6	0.919	2004	Chronic headache	Clinical trial
9	6	0.979	2005	Chinese diagnose	Clinical trial
10	5	0.920	2009	Clinical trial	Placebo effect
11	4	0.983	2018	Economic analysis	Clinical trial

Note: The cluster analysis results mainly include cluster ID, mean year, size, silhouette, label (LLR), and label (MI). Cluster ID is the number after clustering, and Size represents the number of members contained in the cluster. The larger the Size is, the smaller the number. Mean Year represents the average year of the literature in the cluster, which can be used to judge the distance of the cited literature in the cluster. The larger the log-likelihood ratio (LLR) is, the more representative the cluster category; mutual information (MI) is mainly used to represent the relationship between terms and categories in text mining, and it does not consider the frequency of feature words.