The study looked at how China's different regions have grown economically from 1985 to 2007. They found that while there was overall progress in the long term, there wasn't consistent growth in the short term. This means that some regions were catching up with others over time, but not always quickly. The researchers used a method called OLS to analyze the data and found that there was a pattern of conditional convergence, where regions with lower economic growth tended to catch up to those with higher growth rates.