Abstract Online health communities (OHCs) function as significant platforms that people use to obtain information and emotional support. Despite many studies on user behavior and relationships, little attention has been paid to user identities and how different layers of identities are interwoven. To address this potential research gap, this study examined users' relationship‐layer identities and their evolution by elaborating on the communication theory of identity (CTI) and social support theory. Additionally, based on our previous study on users' personal‐layer identities in OHCs, we investigated how users' relationship‐layer identities interacted with their personal‐layer identities. This study classified users' posts and replies into providing informational support, seeking informational support, providing emotional support, seeking emotional support, and companionship using the bidirectional encoder representation from transformers (BERT), with F1‐scores above 0.848. Through social network analysis, this study found that users of OHCs constructed their relationship‐layer identities more through informational interactions than through emotional interactions. Users with various personal‐layer identities presented different relationship‐layer identities. Users' relationships were more initiated by information exchange, and users with more interactions had more companionship activities. OHCs provided efficient communication channels for people to exchange social support.

This study investigates the content of questions and responses about the Zika virus on Yahoo! Answers as a recent example of how public concerns regarding an international health issue are reflected in social media. We investigate the contents of posts about the Zika virus on Yahoo! Answers, identify and reveal subject patterns about the Zika virus, and analyze the temporal changes of the revealed subject topics over 4 defined periods of the Zika virus outbreak. Multidimensional scaling analysis, temporal analysis, and inferential statistical analysis approaches were used in the study. A resulting 2‐layer Zika virus schema, and term connections and relationships are presented. The results indicate that consumers’ concerns changed over the 4 defined periods. Consumers paid more attention to the basic information about the Zika virus, and the prevention and protection from the Zika virus at the beginning of the outbreak of the Zika virus. During the later periods, consumers became more interested in the role that the government and health organizations played in the public health emergency.

Relevance judgment plays an extremely significant role in information retrieval. This study investigates the differences between American users and Chinese users in relevance judgment during the information retrieval process. 384 sets of relevance scores with 50 scores in each set were collected from 16 American users and 16 Chinese users as they judged retrieval records from two major search engines based on 24 predefined search tasks from 4 domain categories. Statistical analyses reveal that there are significant differences between American assessors and Chinese assessors in relevance judgments. Significant gender differences also appear within both the American and the Chinese assessor groups. The study also revealed significant interactions among cultures, genders, and subject categories. These findings can enhance the understanding of cultural impact on information retrieval and can assist in the design of effective cross-language information retrieval systems.