prepare_longitudinal_data: Prepare Wide-Format Longitudinal PROM Data

In grmtree: Recursive Partitioning for Graded Response Models

Prepare Wide-Format Longitudinal PROM Data

Description

Constructs a wide-format data frame suitable for longitudinal_grmtree from separate Time 1 and Time 2 item response columns. The function creates a matrix-valued column containing the concatenated T1 and T2 responses, along with any specified covariates.

Usage

prepare_longitudinal_data(
  data,
  items_t1,
  items_t2,
  covariates = NULL,
  id = NULL
)

Arguments

data	A data frame containing item response columns for both time points and any covariates.
items_t1	Character vector of column names for Time 1 item responses, in the order they should appear in the response matrix.
items_t2	Character vector of column names for Time 2 item responses, in the same order as items_t1. Must have the same length.
covariates	Optional character vector of column names for covariates to include in the output data frame (e.g., c("age", "sex")).
id	Optional character string specifying the subject ID column name. If provided, the ID column is included in the output.

Value

A data frame with:

Covariates

All columns specified in covariates

resp_wide

A matrix-valued column with 2 * length(items_t1) columns. The first half contains T1 responses (named Item1_T1, ..., ItemM_T1) and the second half contains T2 responses (named Item1_T2, ..., ItemM_T2).

Rows with any missing values in the response matrix are removed, with a message indicating how many rows were dropped.

See Also

longitudinal_grmtree for fitting the tree

Examples

library(grmtree)

# Load the synthetic longitudinal data
data("grmtree_long_data", package = "grmtree")

  # Prepare the wide-format response matrix from separate T1 and T2 columns
  items_t1 <- c("MOS_Listen", "MOS_Info", "MOS_Advice_Crisis", "MOS_Confide",
                "MOS_Advice_Want", "MOS_Fears", "MOS_Personal", "MOS_Understand")
  ld <- prepare_longitudinal_data(
    data = grmtree_long_data,
    items_t1 = items_t1,
    items_t2 = paste0(items_t1, "_year1"),
    covariates = c("sex", "age", "residency", "job",
                   "education", "comorbidity_count", "ever_smoker")
  )

  # Check structure
  str(ld$resp_wide)  # 1500 x 16 matrix

grmtree documentation built on Sept. 2, 2026, 1:07 a.m.