why it can't be economic migration? While it seems that China has somewhat higher income in average, but it does not mean they are rich. Even in richer provinces, there are lots of people living below poverty line, not to mention a relatively less developed region like Tibet. Economic well-being is quite likely to be one reason.
Even if they are richer than the Tibetans in India, they may not have that information.
Also since Dalai Lama is one of the two most influential schools of Tibentan Buddhism, it's quite possible for them to go to where their spiritual leader lives. This is a pure religious issue, has nothing to do with persecution or whatever.
Finally, you cannot deduce a macro effect from only one occurence, you need enough data so that you can prove the hypothesis that "there are more tibetans leaving China than entering China". Even if it is true, you still have to get enough evidence to prove that this outflow is due to persecution.
Even if they are richer than the Tibetans in India, they may not have that information.
Also since Dalai Lama is one of the two most influential schools of Tibentan Buddhism, it's quite possible for them to go to where their spiritual leader lives. This is a pure religious issue, has nothing to do with persecution or whatever.
Finally, you cannot deduce a macro effect from only one occurence, you need enough data so that you can prove the hypothesis that "there are more tibetans leaving China than entering China". Even if it is true, you still have to get enough evidence to prove that this outflow is due to persecution.