India's rank and global share in scientific research -- how data sourced from different databases can produce varying outcomes

India is emerging as a major knowledge producer of the world in terms of proportionate share of global research output and the overall research productivity rank. Many recent reports, both of commissioned studies from Government of India as well as independent international agencies, show India at different ranks of global research productivity (variations as large as from 3rd to 9th place). The paper examines this contradiction; tries to analyse as to why different reports places India at different ranks and what may be the reasons thereof. The research output data for India, along with the ten most productive countries in the world, is analysed from three major scholarly databases: Web of Science, Scopus and Dimensions for this purpose. Results show that both, the endogenous factors (such as database coverage variation and different subject classification schemes) and the exogenous factors (such as subject selection and publication counting methodology) cause the variations in different reports. This paper reports first part of the analysis, focusing mainly on variations due to use of data from different databases. The policy implications of the study are also discussed.