format
A list providing a summary of the data. The list contains:
lcl{
bloodpressure$means : the mean vector,
bloodpressure$stddev : the vector of standard deviations,
bloodpressure$corr : the correlation matrix, and
bloodpressure$n : the sample size.
}source
Whittaker, J. (1990) Graphical models in applied
multivariate statistics. Chichester: Wiley. (See p.343).