construct_covmat {LTFHPlus}

Constructing a covariance matrix for a variable number of phenotypes

Description

construct_covmat returns the covariance matrix for an underlying target individual and a variable number of its family members for a variable number of phenotypes. It is a wrapper around construct_covmat_single and construct_covmat_multi.

Usage

construct_covmat(
  fam_vec = c("m", "f", "s1", "mgm", "mgf", "pgm", "pgf"),
  n_fam = NULL,
  add_ind = TRUE,
  h2 = 0.5,
  genetic_corrmat = NULL,
  full_corrmat = NULL,
  phen_names = NULL
)

Arguments

fam_vec

A vector of strings holding the different family members. All family members must be represented by strings from the following list:

• m (Mother)

• f (Father)

• c[0-9]*.[0-9]* (Children)

• mgm (Maternal grandmother)

• mgf (Maternal grandfather)

• pgm (Paternal grandmother)

• pgf (Paternal grandfather)

• s[0-9]* (Full siblings)

• mhs[0-9]* (Half-siblings - maternal side)

• phs[0-9]* (Half-siblings - paternal side)

• mau[0-9]* (Aunts/Uncles - maternal side)

• pau[0-9]* (Aunts/Uncles - paternal side). Defaults to c("m","f","s1","mgm","mgf","pgm","pgf").

n_fam

A named vector holding the desired number of family members. See setNames. All names must be picked from the list mentioned above. Defaults to NULL.

add_ind

A logical scalar indicating whether the genetic component of the full liability as well as the full liability for the underlying individual should be included in the covariance matrix. Defaults to TRUE.

h2

Either a number representing the heritability on liability scale for one single phenotype or a numeric vector representing the liability-scale heritabilities for a positive number of phenotypes. All entries in h2 must be non-negative and at most 1.

genetic_corrmat

Either NULL or a numeric matrix holding the genetic correlations between the desired phenotypes. All diagonal entries must be equal to one, while all off-diagonal entries must be between -1 and 1. In addition, the matrix must be symmetric. Defaults to NULL.

full_corrmat

Either NULL or a numeric matrix holding the full correlations between the desired phenotypes. All diagonal entries must be equal to one, while all off-diagonal entries must be between -1 and 1. In addition, the matrix must be symmetric. Defaults to NULL.

phen_names

Either NULL or a character vector holding the phenotype names. These names will be used to create the row and column names for the covariance matrix. If it is not specified, the names will default to phenotype1, phenotype2, etc. Defaults to NULL.

Details

This function can be used to construct a covariance matrix for a given number of family members. If h2 is a number, each entry in this covariance matrix equals the percentage of shared DNA between the corresponding individuals times the liability-scale heritability

h^2

. However, if h2 is a numeric vector, and genetic_corrmat and full_corrmat are two symmetric correlation matrices, each entry equals either the percentage of shared DNA between the corresponding individuals times the liability-scale heritability

h^2

or the percentage of shared DNA between the corresponding individuals times the correlation between the corresponding phenotypes. The family members can be specified using one of two possible formats.

Value

If either fam_vec or n_fam is used as the argument, if it is of the required format, if add_ind is a logical scalar and h2 is a number satisfying

0 \leq h2 \leq 1

, then the function construct_covmat will return a named covariance matrix, which row- and column-number corresponds to the length of fam_vec or n_fam (+ 2 if add_ind=TRUE). However, if h2 is a numeric vector satisfying

0 \leq h2_i \leq 1

for all

i \in \{1,...,n_pheno\}

and if genetic_corrmat and full_corrmat are two numeric and symmetric matrices satisfying that all diagonal entries are one and that all off-diagonal entries are between -1 and 1, then construct_covmat will return a named covariance matrix, which number of rows and columns corresponds to the number of phenotypes times the length of fam_vec or n_fam (+ 2 if add_ind=TRUE). If both fam_vec and n_fam are equal to c() or NULL, the function returns either a 2 \times 2 matrix holding only the correlation between the genetic component of the full liability and the full liability for the individual under consideration, or a

(2 \times n_pheno) \times (2\times n_pheno)

matrix holding the correlation between the genetic component of the full liability and the full liability for the underlying individual for all phenotypes. If both fam_vec and n_fam are specified, the user is asked to decide on which of the two vectors to use. Note that the returned object has different attributes, such as fam_vec, n_fam, add_ind and h2.

See Also

get_relatedness, construct_covmat_single, construct_covmat_multi

Examples

construct_covmat()
construct_covmat(fam_vec = c("m","mgm","mgf","mhs1","mhs2","mau1"), 
                 n_fam = NULL, 
                 add_ind = TRUE, 
                 h2 = 0.5)
construct_covmat(fam_vec = NULL, 
                 n_fam = stats::setNames(c(1,1,1,2,2), c("m","mgm","mgf","s","mhs")), 
                 add_ind = FALSE,
                 h2 = 0.3)
construct_covmat(h2 = c(0.5,0.5), genetic_corrmat = matrix(c(1,0.4,0.4,1), nrow = 2),
                 full_corrmat = matrix(c(1,0.6,0.6,1), nrow = 2))