Questions to the Article: Exploring the Shift in International Trends in Mobile Health Research From 2000 to 2020 (Preprint)

UNSTRUCTURED The article published on September 9, 2021, is well-written and of interest, but remains two questions that are required for clarifications, such as the ways (1) to construct the growth curve and (2) to determine the flashpoint(or, say, inflection point, IP) on the growth curve shown in Figure 3. The authors addressed that the year 2015 was a flashpoint on the curve(ie. y = 37e0.3062x, with R2=0.9935) and determined the flash point by the naked eye. Although numerous bibliometric analyses applied the cumulative publications to release information about the growth curve and the IP using a particular formula, none of such research proposed an appropriate way to determine the IP. Accordingly, we are motivated to propose an item response theory (IRT) model(IRT) to determine the IP on a given ogive curve and found that the IP is in 2017 instead of 2015 with R2=0.9797 rather than 0.9935 in the questionable article. Similarly, the real model coefficient and R2 are 0.2942 and 0.9954, respectively, if the growth curve is modeled by the formula(= 37ebx ) in Microsoft Excel using the Solver add-in tool demonstrated in this article. The ITR model used to determine the IP location on cumulative time-series data is recommended to future relevant studies, not merely limited to the bibliometric analysis.