Static and Dynamic Impacts of Internet Use on Self-Rated Health among Adults in China: A Hybrid Model Analysis Based on National Panel Survey Data.

The widespread use of the Internet has a substantial impact on people's livelihoods, including health-related factors. Whether this impact is beneficial or harmful to people's health remains unclear. Some cross-sectional studies found static differences in the health status between Internet users and nonusers, whereas panel data studies found dynamic changes in an individuals' health over time, making the issue, including its causality, controversial. Therefore, we aimed to clarify the association between the use of the Internet and people's health from both static and dynamic aspects. Data were obtained for 46,460 adults from the China Family Panel Studies in 2014, 2016, and 2018. The analysis applied a logistic regression hybrid model with self-rated health as the dependent variable and Internet use as the main independent variable. In the hybrid model, time-varying independent variables were decomposed into between-individual (static) differences and within-individual (dynamic) changes over time. The results indicated that the between-individual coefficient of Internet use was significantly positive, but the within-individual coefficient was not, i.e., Internet users felt healthier than nonusers from the static aspect but starting to use the Internet did not increase the self-rated health from the dynamic aspect. These findings suggest that attention is needed in order to not confuse the static differences with dynamic change regarding the causality between Internet use and self-rated health.