A study by Amanda Gregg (The American Economic Review, 2020) compares factory productivity among corporations and non-corporations in late Imperial Russia, and finds that corporations outperformed. I identify a significant number of mistakes in Gregg’s primary data; these mistakes render the results unsubstantiated. I also find that the correlation analysis does not allow for a fair comparison between corporations and non-corporations because it does not take into account the differences between the two. Further, I find that the fixed-effects analysis does not guarantee a causal effect because it does not account for historical context. Lastly, I determine that the instrumental variables method is unreliable. My findings suggest that the claimed causal relationship between the corporate form and productivity remains unestablished.