DF = data.frame( sector=c( rep( 'Variety_1', 3 ), rep( 'Variety_2', 3 ), rep( 'Variety_3', 3 ), rep( 'Variety_4', 3 ), rep( 'Variety_5', 3 ) ), yield=c( 46.2, 51.9, 48.7, 49.2, 58.6, 57.4, 60.3, 58.7, 60.4, 48.9, 51.4, 44.6, 52.5, 54.0, 49.3 ) )