* SUR - 2 Period Crossover Design with Changing Covariate;

data patel;



group     x     y1      z1      y2      z2     x1    x2

-------------------------------------------------------

  1       1    1.28    1.09    1.33    1.24     1     0

  1       1    1.60    1.38    2.21    1.90     1     0

  1       1    2.46    2.27    2.43    2.19     1     0

  1       1    1.41    1.34    1.81    1.47     1     0

  1       1    1.40    1.31    0.85    0.85     1     0

  1       1    1.12    0.96    1.20    1.12     1     0

  1       1    0.90    0.66    0.90    0.78     1     0

  1       1    2.41    1.69    2.79    1.90     1     0

  1      -1    3.06    1.74    1.38    1.54     0     1

  1      -1    2.68    2.41    2.10    2.13     0     1

  1      -1    2.60    3.05    2.32    2.18     0     1

  1      -1    1.48    1.20    1.30    1.41     0     1

  1      -1    2.08    1.70    2.34    2.21     0     1

  1      -1    2.72    1.89    2.48    2.05     0     1

  1      -1    1.94    0.89    1.11    0.72     0     1

  1      -1    3.35    2.41    3.23    2.83     0     1

  1      -1    1.16    0.96    1.25    1.01     0     1