The research that is believed to be the largest epidemiological study of Covid-19 was conducted in two Indian states, Andhra Pradesh and Tamil Nadu, and has revealed several important findings. Although it did involve a large number of confirmed Covid-19 cases, the study only examined cases and traced contacts in India, and this factor can both strengthen and hinder the validity of the study.
On the one hand, internal validity could be strengthened by the fact that the study was limited to the Indian population only. This setting made it easier for researchers to exclude certain factors, applicable to other nations, that could have had an impact on the findings of the study. As a result, several surprising conclusions were made concerning the country’s morbidity and mortality rates. For example, it has been revealed that, unlike in other countries, the overall-case mortality rates declined with age, making people over 65 “more likely to survive the virus” (The 5 biggest surprises, 2020, par. 7). This may be caused by the fact that the overall life expectancy in the country is about 69. Consequently, most people who live over 65 may have better living conditions or health status in general. In any case, this conclusion would not be made unless the study was limited to the Indian population, as it is characteristic of this country only.
In turn, external validity is hindered because almost all participants of the study belonged to a lower-income population when compared to other nations. At the same time, they were residents of the two states that were “best prepared to deal with an outbreak” (The 5 biggest surprises, 2020, par. 13). Because of this, it may be challenging to apply the study’s findings in other settings.
References
The 5 biggest surprises in the largest-ever study of COVID-19. (2020). Advisory Board.