sentences:  However, in 2000 Lott was unable to produce the data or any records showing that the survey had been undertaken.He said the 1997 hard drive crash that had affected several projects with co-authors had destroyed his survey data set, the original tally sheets had been abandoned with other personal property in his move from Chicago to Yale, and he could not recall the names of any of the students who he said had worked on it.Critics alleged that the survey had never taken place, but Lott defends the survey's existence and accuracy, quoting on his website colleagues who lost data in the hard drive crash or who remember Lott relating the incident back when the crash allegedly occurred.