A sample of four-month-old start-ups echoes this finding: as many as 87 percent of new entrepreneurs expect to survive at least three years in business, whereas the actual statistical survival rate is around 60 percent.
Link
http://econpapers.repec.org/scripts/redir.pl?u=http%3A%2F%2Fwww.etla.fi%2Ffiles%2F1345_Dp987.pdf;h=repec:rif:dpaper:987