exams.forge (version 1.0.10)

ddiscrete2: Bivariate Discrete Probability Function

Description

Creates a bivariate discrete probability function based on the marginal probability functions row and col. If unit is not given then unit will be the product of the units used in row and col, otherwise it will appear as the least common multiple unit product of the units used in row and col. If target is NA then the common distribution of two independent random variables is returned, otherwise an iterative algorithm is run to approach a target association or correlation measure, see also assoc_data() (called internally). zero allows for zero entries in the common distribution. FUN computes the association or correlation measures based on a frequency table. tol gives the maximal deviation of the association or correlation measure and the target value. maxit limits the number of steps. Please note that a solution is not guaranteed, especially for extreme values for target, for example for \(+1\), \(-1\) or nearby values. If attr(joint, "iterations")==maxit then you need either to increase maxit, to decrease tol or to check if you have chosen an appropriate target value (for a nominal measure in \(0 <= target <= 1\), for ordinal measure in \(-1 <= target <= +1\)).

Usage

ddiscrete2(
  row,
  col,
  unit = NULL,
  zero = FALSE,
  FUN = nom.cc,
  target = NA,
  tol = 0.001,
  maxit = 500,
  ...
)
biv_discrete_prob(
  row,
  col,
  unit = NULL,
  zero = FALSE,
  FUN = nom.cc,
  target = NA,
  tol = 0.001,
  maxit = 500,
  ...
)

Value

A bivariate discrete probability function.

Arguments

row

numeric: marginal row distribution

col

numeric: marginal col distribution

unit

integer: reciprocal of the smallest non-zero probability (default: NULL)

zero

logical: zeros are allowed in the final probabilities (default: FALSE)

FUN

function: association or correlation function (default: nom.cc)

target

numeric: target association or correlation (default: NA)

tol

numeric: tolerance for target association or correlation (default: 0.001)

maxit

integer: maximal number of iterations (default: 100)

...

further parameters for FUN

Examples

row <- ddiscrete(runif(5))
col <- ddiscrete(runif(3))
joint <- ddiscrete2(row, col)
joint
joint <- ddiscrete2(row, col, target=0.5)
joint
nom.cc(joint*attr(joint, "unit"))