metaSEM: create.Tau2 – R documentation

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create.Tau2

Create a variance component of the heterogeneity of the random effects

Description

It creates variance component of the heterogeneity of the random effects by decomposing the variance component into matrices of correlation and standard deviations.

Usage

create.Tau2(RAM, no.var, Tau1.labels=seq(no.var),
            RE.type = c("Diag", "Symm", "Zero", "User"),
            RE.User=NULL, Transform = c("expLog", "sqSD"),
            RE.startvalues=0.05)

Arguments

`RAM`	The RAM model for testing. `no.var` is calculated from it.
`no.var`	If `RAM` is missing, the user has to specify the `no.var` argument. It represents the `no.var` by `no.var` of the random effects).
`Tau1.labels`	Parameter labels in `Tau1`. The default is `Tau1_1`, `Tau1_2`, etc.
`RE.type`	Either `"Diag"`, `"Symm"`, `"Zero"` or `"User"`. If it is`"Diag"` (the default if missing), a diagonal matrix is used for the random effects meaning that the random effects are independent. If it is `"Symm"`, a symmetric matrix is used for the random effects on the covariances among the correlation (or covariance) vectors. If it is `"Zero"`, a zero matrix is assumed on the variance component of the random effects. If it is `"User"`, users have to specify the `RE.true` argument.
`RE.User`	It represents the `no.var` by `no.var` symmetric matrix of `TRUE` or `FALSE` for the variance component. If the elements are `FALSE`, they are fixed at 0.
`Transform`	Either `"expLog"` or `"sqSD"`. If it is `"expLog"`, the variances are estimated by applying a log and exp transformation. If it is `"sqSD"`, the variances are estimated by applying a square on the SD. The transformation may improve the estimation when the heterogeneity is small or close to zero.
`RE.startvalues`	Starting values for the variances.

Value

A list of MxMatrix-class. The variance component is computed in Tau2.

Author(s)

Mike W.-L. Cheung <mikewlcheung@nus.edu.sg>

Examples

## Not run: 
T0 <- create.Tau2(no.var=4, RE.type="Diag", Transform="expLog", RE.startvalues=0.05)
T0

T1 <- create.Tau2(no.var=4, Tau1.labels=c("a", "b", "c", "d"))
T1

## End(Not run)

metaSEM

Meta-Analysis using Structural Equation Modeling

v1.2.5

GPL (>= 2)

Authors

Mike Cheung [aut, cre] (<https://orcid.org/0000-0003-0113-0758>)

Initial release

2020-11-29