Generates univariate synthetic data using linear regression
  of an outcome variable transformed by natural logarithm (lognorm), 
  square root (sqrtnorm) or cube root (cubertnorm).
syn.lognorm(y, x, xp, proper = FALSE, ...) 
syn.sqrtnorm(y, x, xp, proper = FALSE, ...)
syn.cubertnorm(y, x, xp, proper = FALSE, ...)an original data vector of length n.
a matrix (n x p) of original covariates.
a matrix (k x p) of synthesised covariates.
a logical value specifying whether proper synthesis should be conducted. See details.
additional parameters.
A vector of length k with synthetic values of y.
Generates synthetic values using the spread around the
  fitted linear regression line of transformed y given x.
  For proper synthesis first the regression coefficients are drawn
  from normal distribution with mean and variance from the fitted model.
  The synthetic values are transformed back to the original scale.