format
A list providing a summary of the data. The list contains:
lcl{
glucose$means : the mean vector,
glucose$stddev : the vector of standard deviations,
glucose$corr : the correlation matrix, and
glucose$n : the sample size.
}source
Cox, D.R. & Wermuth, N. (1993) Linear Dependencies Represented by
Chain Graphs. Statistical Science 8(3): 204-283. (See Table 7).