~~Scientist Doubt~~

   Since I work in the observatory I have chance to meet few scientists who work there and learn about the stuff they do. Today morning when I went to office my supervisor told one of the scientist needs a clarification with the research he is doing and asked me whether I could help him out. Once I said sure, he fixed an appointment with him for lunch.
  Since we used to bring lunch ,we met in the nearby park and sat in one of the picnic benches. He is working  on the project using  night time lights for which they use the services of the satellites. These satellites instead of taking weird pictures of stones in space takes pictures of different places of earth in the night. Using the intensity of a light at a place they predict the economic activity and carbon emissions at the location. They have data over the period last 15 years for all the countries. So the normal conclusion they derived was the light intensity has increased over the last decade.
  So while studying the data for India he found the erratic trend there has been light intensity increases in some regions but there were few areas where the intensity has gone down over the decade. He was asking whether some mass migrations have happened from rural to urban areas. It was easy for me to see the problem from an Indian perspective and I told him the reason. He told me my hypothesis is more meaningful than what others had told him and told the 30 minute lunch break was the time well spent.
 So guys can you guess what have caused this erratic trend?