Poverty Percentage of Nepal

The comparison of poverty percentage from three living standard survey of Nepal shows poverty percentage  has decreased from 41.8 percent in 1994/95 to 25.16 in 2010/11. But the worrying situation here is about the urban poverty and poverty in far western region of Nepal. There was  only 9.6 percent of population below poverty line in urban area during second living standard survey which has gone up to reach 15.46 in third living standard survey. Migration of poor and  landless people toward urban area in search of better employment is believed to be the reason behind this. But if this trend continues, our urban areas would be full of poor very soon. Now increased poverty in far western region from 41 percent in second living standard survey to 45.61 in third NLSS  is matter of confusion. Many logic may be there to explain it. First, the living standard survey is a sample survey, was there sampling error?? Second, the level of income for poverty line has increased in third living standard survey. So the far western region might not have increased to catch up the overall national growth of income standard??