design.efficiency: Create the design matrix, variance-covariance matrix, the variance of each
pairwise comparison and the efficicency of each pairwise comparison for a
cross-over design
Description
Function to read in a cross-over design and create the design matrix X, the
variance-covariance matrix of the parameter estimates (X'X)^-1, the variance
of each pairwise comparison and the efficicency of each pairwise comparison.