Neither were as successful as they anticipated. The migrants sent there weren’t taught how to grow local crops so would plant lowland crops with predictable failure. Malaria was a problem, and subsidizes for the migrants would sometimes run out before their farms were self-sufficient. But the local minorities groups usually helped the newcomers and people would learn from their mistakes. Some died, but half of the first wave of pioneers to my home state of Iowa died, too, from summer diseases and winter freezes.
Most of his data came from interviewing senior citizens who had participated in the migration, either has migrants or cadres. In the appendix he explains that a quantitative study is hindered by inaccurate record keeping. Early on, villages paid their taxes as a collective based upon population, so had incentive to lie about their numbers, and later on many cadres were more concerned about looking good on paper than the future needs of sociologists. His first chapter is mostly about the amusing difficulty of finding a particular village because its name had changed over time, conflicting stories about its location, and the road conditions.
Many Vietnamese ask me if I see any difference between themselves and Chinese, and now I do have an answer, not just from this book but a couple of Vietnamese novels I’ve read (in translation). I think Vietnamese are more concerned with consensus than Chinese are. They want to talk things out and come to general agreement. In the Vietnamese Communist Party, cadres were considered better at their jobs if they managed by persuasion than ordered by fiat.