As per Mr. Singh's(from TISS) findings , 37% (or 2 million) are Maharashtrians, 25% from UP/Bihar and rest from other parts of the country. This implies a whopping 73% of migrants into Mumbai are non-Maharshtrians! This finding seems to be a contradiction to the front page headline that Maharashtrians constitute 67% of migrants into Mumbai.
It should also be noted that the last census survey (as opposed to a sample survey) has been carried out in 2001 and a good 7 years have passed hence, with the population in Mumbai rising at a high rate. A direct impact of this, as any common man can vouch for in Mumbai, can be felt in the inadequacy of Mumbai's infrastructure to handle the increased population despite new projects being launched.
Further, in my opinion, it is imprudent to ignore or underestimate causes taken up by shrewd politicians on either side. Today's politics is based on vote-bank numbers which are based on ground realities and not purely academic surveys.
Lastly the results are based on a sample survey and not a census count and that too it is not a 'random sample' and very likely may not ha Lastly the results are based on a sample survey and not a census count and that too it is not a 'random sample' and very likely may not have enough data vis-a-vis the huge population size to make a meaningful conclustion on the specific hypothesis of non-Maharashtrians migrating to Mumbai.