list(N= 12,
			Y = structure(
				.Data = c(1,1,
				               1,-1,
				               -1,1,
				              -1, -1,
				               2, NA,
				               2, NA,
				              -2, NA,
				              -2, NA,
				               NA, 2,
				               NA, 2,
				               NA, -2,
				               NA, -2),
				    .Dim = c(12, 2)))