Researchers trying to compare economic data of the USSR and capitalist countries face questions of the comprehensiveness, accessibility, and reliability of data on Soviet economic production and growth. At an online seminar hosted by the HSE University International Centre for the History and Sociology of World War II and its Consequences, Assistant Professor Ilya Voskoboynikov (Faculty of Economic Sciences, HSE University) presented an overview of available approaches to studying the absolute size of the Soviet economy and its growth rates.