What do you think about this study about Stalins economic growth.

So I was debating with someone about the Stalin and was arguing that his policies were necessary for Soviet economic development. He countered my statements with this study Was Stalin Necessary for Russia's Economic Development?https://ift.tt/2YK4DCN my economic background isn't solid enough to understand how they build this model. Did any of you hear of this study and what do you make of it? via /r/communism https://ift.tt/3hH3690