Data from a 2x2 crossover trial on cerebrovascular deficiency adapted from
Jones and Kenward (1989, p.90), where treatment A and treatment B are active
drug and placebo, respectively.  The outcome indicates if an electrocardiogram 
was judged abnormal (0) or normal (1).

##

                Responses               Period
         -----------------------       ---------
Group   (1,1) (0,1) (1,0) (0,0)  Total   1   2 
-------------------------------------------------
AB       22    0      6     6     34    28   22
BA       18    4      2     9     33    20   22
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