list(M = 4, N = 20, Y = structure(
      .Data = c(47.8, 48.8, 49.0, 49.7,
               46.4, 47.3, 47.7, 48.4,
               46.3, 46.8, 47.8, 48.5,
               45.1, 45.3, 46.1, 47.2,
               47.6, 48.5, 48.9, 49.3,
               52.5, 53.2, 53.3, 53.7,
               51.2, 53.0, 54.3, 54.5,
               49.8, 50.0, 50.3, 52.7,
               48.1, 50.8, 52.3, 54.4,
               45.0, 47.0, 47.3, 48.3,
               51.2, 51.4, 51.6, 51.9,
               48.5, 49.2, 53.0, 55.5,
               52.1, 52.8, 53.7, 55.0,
               48.2, 48.9, 49.3, 49.8,
               49.6, 50.4, 51.2, 51.8,
               50.7, 51.7, 52.7, 53.3,
               47.2, 47.7, 48.4, 49.5,
               53.3, 54.6, 55.1, 55.3,
               46.2, 47.5, 48.1, 48.4,
               46.3, 47.6, 51.3, 51.8),
            .Dim = c(20, 4)),
   age = c(8.0, 8.5, 9.0, 9.5), 
      R = structure(
            .Data = c(1, 0, 0, 0, 
                     0, 1, 0, 0, 
                     0, 0, 1, 0, 
                     0, 0, 0, 1), .
            Dim = c(4, 4)))