Last year, investment in real estate tech startups totaled more than $6 billion, which isn’t surprising given the implications of big data on the housing economy. Everything from evaluating risk management to analyzing the next trend in housing depends on gathering “clean” information on mortgage borrowers and home sellers. But one group remains largely absent from this data collection, and this is the group that most intrigued a panel of big data experts assembled by Amherst InsightLabs at the SXSW conference and festivals on Sunday.