DF = data.frame(
    type=as.factor( c( rep( 'A', 15 ), rep( 'B', 15 ), rep( 'C', 15 ) ) ),
    time=c(
        19, 23, 26, 18, 20, 20, 18, 35, 27, 31, 25, 22, 23, 27, 29,
        20, 20, 32, 27, 40, 24, 22, 18, 24, 25, 29, 31, 24, 25, 32,
        16, 26, 15, 18, 19, 17, 19, 18, 14, 18, 19, 21, 17, 19, 18 )
)