pdSRM: Construct the pdSRM object

In roundRobinR: Manipulate and Analyze Round Robin Dyadic Data

Construct the pdSRM object

Description

Creates the positive-definite matrix class used to specify the actor-partner covariance structure of the Social Relations Model within lme. This class enforces the SRM constraint that all actors share a single variance, all partners share a single variance, and a single actor-partner covariance (generalized reciprocity) is estimated.

Usage

pdSRM(
  value = numeric(0),
  form = NULL,
  nam = NULL,
  data = sys.frame(sys.parent())
)

Arguments

value	an optional initialization value, inherited from pdMat
form	an optional one-sided linear formula specifying the row/column names for the matrix
nam	an optional vector of character strings specifying the row/column names for the matrix
data	inherited from the surrounding nlme call

Value

a pdMat object representing a positive-definite matrix conforming to the SRM covariance structure

References

Knight, A. P., & Humphrey, S. E. (2019). Dyadic data analysis. In S. E. Humphrey & J. M. LeBreton (Eds.), The Handbook for Multilevel Theory, Measurement, and Analysis (pp. 423–447). American Psychological Association. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1037/0000115-019")}

Snijders, T. A. B., & Kenny, D. A. (1999). The social relations model for family data: A multilevel approach. Personal Relationships, 6, 471–486. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1111/j.1475-6811.1999.tb00204.x")}

Examples

d <- createDummies(
  group.id = "groupId", act.id = "actId", part.id = "partId",
  d = sampleDyadData[sampleDyadData$timeId == 1, ],
  merge.original = TRUE
)
o <- nlme::lme(
  liking ~ 1,
  random = list(groupId = nlme::pdBlocked(list(
    nlme::pdIdent(~1),
    pdSRM(~ -1 + a1 + a2 + a3 + a4 + p1 + p2 + p3 + p4)
  ))),
  correlation = nlme::corCompSymm(form = ~1 | groupId / pdSRM_dyad_id),
  data = d,
  na.action = stats::na.omit
)

roundRobinR documentation built on Sept. 18, 2026, 1:06 a.m.