This function estimates the parameters of the Polynomial Density-Quantile4 distribution given the L-moments of the data in an L-moment object such as that returned by lmoms. The relations between the distribution parameters and L-moments are seen under lmompdq4.
parpdq4(lmom, checklmom=TRUE, snapt4uplimit=TRUE)An R
list is returned.
The type of distribution: pdq4.
The parameters of the distribution.
A numeric field connected to the ifailtext; a value of 0 indicates fully successful operation of the function.
A message, instead of a warning, about the internal operations or operational limits of the function.
The source of the parameters: “parpdq4”.
An L-moment object created by lmoms or vec2lmom.
Should the lmom be checked for validity using the are.lmom.valid function. Normally this should be left as the default and it is unlikely that the L-moments will not be viable. However, for some circumstances or large simulation exercises then one might want to bypass this check.
A logical controlling the behavior of the function for \(\tau_4\) exceeding an operational upper margin and whether the incoming \(\tau_4\) can be snapped down to this margin (see Note).
W.H. Asquith
Hosking, J.R.M., 2007, Distributions with maximum entropy subject to constraints on their L-moments or expected order statistics: Journal of Statistical Planning and Inference, v. 137, no. 9, pp. 2870--2891, tools:::Rd_expr_doi("10.1016/j.jspi.2006.10.010").
lmompdq4, cdfpdq4, pdfpdq4, quapdq4