list(tau = structure(.Data = c(0.5,0,0,0.5), .Dim = c(2,2)),
      Y = structure(
            .Data = c(NA,NA,
            NA,NA,
            NA,NA,
            NA, NA,
            NA, 2,
            NA, 2,
            NA, 2,
            NA, 2,
            3, NA,
            3, NA,
            3, NA,
            3, NA),
            .Dim = c(12, 2)))