A lot of people have pointed of culture and language, and this has been two of the most important things for me when I've had to make the choice between program

A lot of people have pointed of culture and language, and this has been two of the most important things for me when I've had to make the choice between programmers. Most of the time, as long as the hire is above a certain skill level, the bottleneck is absolutely the communication bandwidth between you and them. If they don't completely understand things or you don't understand them, the number of round trips increases. Add to a general sheepishness when presented with American English and slang, as well as certain cultural tendencies, and you encounter a lot of hires who will say yes (especially from India and Vietnam) when they don't understand. This is a big problem. I've also seen the efficient market at work, but on a level up from the programmers themselves. In a lot of cases, programmers from developing countries are hired out by agencies who will charge a lot closer to market while paying them less. This might cause a lot of the disparities in the data looked at by the author, and in any data where salaries are compared directly.