A report by the American Association for the Advancement of Science using quantitative methods (based on records of flight) and refugees' accounts to examine what led to the exodus of over 850,000 people from Kosovo in seven weeks in the spring of 1999 concludes: "Yugoslav authorities planned and implemented a centrally organized campaign to clear at least certain regions of ethnic Albanians....A campaign on this scale required detailed advance planning....NATO's bombing was tactically ineffective at stopping the forced eviction of Kosovar Albanians....Only a small fraction of Kosovar Albanians fled Kosovo as a direct result of NATO bombing raids." The report, "Policy or Panic? The Flight of Ethnic Albanians from Kosovo March-May 1999" by Patrick Ball can be found at http://hrdata.aaas.org/kosovo/policyorpanic/.