didec | R Documentation |
The directed dependence coefficient (didec
) estimates the degree of directed dependence of a random vector Y on a random vector X, based on an i.i.d. sample of (X,Y).
didec(X, Y, perm = FALSE, perm.method = c("decreasing"))
X |
A numeric matrix or data.frame/data.table. Contains the predictor vector X. |
Y |
A numeric matrix or data.frame/data.table. Contains the response vector Y. |
perm |
A logical. If |
perm.method |
An optional character string specifying a method for permuting the response variables. This must be one of the strings |
The directed dependence coefficient (didec) is an extension of Azadkia & Chatterjee's measure of directed dependence (Azadkia & Chatterjee, 2021) to a vector of response variables introduced in (Ansari & Fuchs, 2023).
Its calculation is based on the function codec
which estimates Azadkia & Chatterjee’s measure of directed dependence and is provided in the R package FOCI
.
By definition, didec
is invariant with respect to permutations of the variables within the predictor vector X. Invariance with respect to permutations within the response vector Y is achieved by computing the arithmetic mean over all possible (or chosen) permutations.
In addition to the option "full"
of running all q!
permutations of (1, ..., q)
, less computationally intensive options are also available (here, q
denotes the number of response variables): a random selection of q
permutations "sample"
, cyclic permutations such as (1,2,...,q)
, (2,...,q,1)
either "increasing"
or "decreasing"
.
Note that when the number of variables q
is large, choosing "full"
may result in long computation times.
The degree of directed dependence of the random vector Y on the random vector X.
Yuping Wang, Sebastian Fuchs, Jonathan Ansari
M. Azadkia, S. Chatterjee, A simple measure of conditional dependence, Ann. Stat. 49 (6), 2021.
J. Ansari, S. Fuchs, A simple extension of Azadkia & Chatterjee's rank correlation to multi-response vectors, Available at https://arxiv.org/abs/2212.01621, 2024.
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