Calculates plotting point positions according to different authors
ppPositions(
n,
method = c("Gringorton", "Cunane", "Filliben", "Blom", "Weibull", "ppoints")
)numeric, the sample size
a character string naming a valid method (see Details)
a vector of class numeric that contains the plotting positions
The following methods can by selected:
"Gringorton" the plotting point positions are
calculated as
$$m_i = \left(i - 0.44\right) / \left(n + 0.12\right)$$
"Cunane" the plotting point positions are
calculated as
$$m_i = \left(i - 0.4\right) / \left(n + 0.2\right)$$
"Blom" the plotting point positions are
calculated as
$$m_i = \left(i - 0.3175\right) / \left(n + 0.25\right)$$
"Filliben" the order statistic medians are calculated as:
$$
m_i = \left\{
\begin{array}{l l}
1 - 0.5^{1/n} & i = 1 \\
\left(i - 0.3175\right)/\left(n + 0.365\right) & i = 2,\ldots, n - 1 \\
0.5^{1/n} & i = n \\
\end{array}\right.
$$
"ppoints" R core's default plotting point positions
are calculated (see ppoints).