Multiple-group Longitudinal Models

Load nlpsem package, dependent packages and set CSOLNP as the optimizer

library(nlpsem)
mxOption(model = NULL, key = "Default optimizer", "CSOLNP", reset = FALSE)

Load pre-computed models

load(system.file("extdata", "getMGroup_examples.RData", package = "nlpsem"))

Load example data and preprocess data

# Load ECLS-K (2011) data
data("RMS_dat")
RMS_dat0 <- RMS_dat
# Re-baseline the data so that the estimated initial status is for the
# starting point of the study
baseT <- RMS_dat0$T1
RMS_dat0$T1 <- RMS_dat0$T1 - baseT
RMS_dat0$T2 <- RMS_dat0$T2 - baseT
RMS_dat0$T3 <- RMS_dat0$T3 - baseT
RMS_dat0$T4 <- RMS_dat0$T4 - baseT
RMS_dat0$T5 <- RMS_dat0$T5 - baseT
RMS_dat0$T6 <- RMS_dat0$T6 - baseT
RMS_dat0$T7 <- RMS_dat0$T7 - baseT
RMS_dat0$T8 <- RMS_dat0$T8 - baseT
RMS_dat0$T9 <- RMS_dat0$T9 - baseT
# Standardize time-invariant covariates (TICs)
## ex1 and ex2 are standardized growth TICs in models
RMS_dat0$ex1 <- scale(RMS_dat0$Approach_to_Learning)
RMS_dat0$ex2 <- scale(RMS_dat0$Attention_focus)
xstarts <- mean(baseT)

Example 1: Fit multiple group bilinear spline LGCM to evaluate the difference in the development of mathematics ability

set.seed(20191029)
MGroup_Math_BLS_LGCM_f <-  getMGroup(
  dat = RMS_dat0, grp_var = "SEX", sub_Model = "LGCM", y_var = "M", t_var = "T",
  records = 1:9, curveFun = "BLS", intrinsic = TRUE, tries = 20
)

Figure1 <- getFigure(
  model = MGroup_Math_BLS_LGCM_f@mxOutput, nClass = 2, cluster_TIC = NULL, grp_var = "SEX",
  sub_Model = "LGCM", y_var = "M", curveFun = "BLS", y_model = "LGCM", t_var = "T",
  records = 1:9, m_var = NULL, x_var = NULL, x_type = NULL, xstarts = xstarts,
  xlab = "Month", outcome = "Mathematics"
)
#> Treating first argument as an object that stores a character
#> Treating first argument as an object that stores a character
show(Figure1)
#> figOutput Object
#> --------------------
#> Trajectories: 1 
#> Figure 1:
#> `geom_smooth()` using method = 'gam' and formula = 'y ~ s(x, bs = "cs")'

Example 2: Fit multiple group negative exponential LGCM with time-invariant covariates (TICs) to evaluate the difference in the development of reading ability. This model includes two growth TICs, baseline values of teacher-reported approach to learning and attentional focus. Point estimates and corresponding standard errors (SEs) of all parameters are presented within the original parameter space.

set.seed(20191029)
MGroup_Read_EXP_LGCM_TIC_r <- getMGroup(
  dat = RMS_dat0, grp_var = "SEX", sub_Model = "LGCM", y_var = "R", t_var = "T",
  records = 1:9, curveFun = "EXP", intrinsic = FALSE,
  growth_TIC = c("ex1", "ex2"), paramOut = TRUE
)

MGroup_Read_EXP_LGCM_TIC_r@Estimates
Figure2 <- getFigure(
  model = MGroup_Read_EXP_LGCM_TIC_r@mxOutput, nClass = 2, cluster_TIC = NULL, grp_var = "SEX",
  sub_Model = "LGCM", y_var = "R", curveFun = "EXP", y_model = "LGCM", t_var = "T",
  records = 1:9, m_var = NULL, x_var = NULL, x_type = NULL, xstarts = xstarts,
  xlab = "Month", outcome = "Reading"
)
show(Figure2)