Martinez 2017 study has been loled to death by night time data analysts familar with the dataset and its limits. It's rudimentry methods only useful to generate clickbait headlines - it's actually that dumb. Every few years he "updates" study with new weak data but not better methods to be republished. I think latest is 3rd revision. For reference, much more sophisticated light study by NBER (by multiple FED economists on one country vs assistant prof on entire world) conducted same year concluded PRC growth was higher than PRC reported GDP, by ~10%. In line with several studies (like CSIS broken abacus) that use much more rigorous methods. But Martinez's democracy vs authoritarian narrative gets republished every few years because the alternate explanation is stupid studies that confirm western biases gets more clicks.

Again, studies using better data/methods that tried to calc PRC GDP and conclude it's been underreported bt 10-20% as of 2010s data. Which makes sense because PRC incentivized to over report population and under report gdp to stay under high income per capita to stretch development perks reserved for developing countries. That's without going into PRC's conservative GDP estimation methods (relative to developed economies) that underestimate imputed vlaues from rent to consumption that would tag on another 10-20%. This has been pattern since the beginning for PRC global integration, i.e. in 80s PRC and IMF used different surveys to negotiate per capita values to base future gdp calcs, IMF wanted $250 vs PRC wanted $150 and settled somewhere under %200. The TLDR is PRC would rather appear poorer than she is on paper.