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Note. All code chunks in this vignette are set to
eval = FALSEto keep CRAN check times within limits, as the bootstrap and permutation procedures are computationally intensive. All code is fully executable in an interactive R session. Precomputed results for all three pipelines are stored ininst/extdata/and can be loaded withreadRDS(system.file("extdata", "results_bin.rds", package = "SEPA"))etc. Full output and figures are reported in the accompanying manuscript (Kim and Grochowalski, 2019, doi:10.1007/s00357-018-9277-7).
The SEPA package implements the Segment Profile Extraction via Pattern Analysis method for row-mean-centered multivariate data. The three automated workflow functions are:
alsi_workflow() — binary data via multiple
correspondence analysis (MCA)alsi_workflow_ordinal() — ordinal Likert-type data via
homals alternating least squares (ALS) optimal scalingcalsi_workflow() — continuous multivariate data via
ipsatized singular value decomposition (SVD)All three pipelines share a common structure:
This example illustrates the alsi_workflow() pipeline
using binary diagnostic data from N = 1,261 individuals assessed for
eating disorders.
data("ANR2", package = "SEPA")
vars <- c("MDD", "DYS", "DEP", "PTSD", "OCD", "GAD", "ANX", "SOPH", "ADHD")
head(ANR2[, vars])Diagnostic prevalence varies substantially: MDD is the most common diagnosis (44.3%), followed by DEP and ANX, while DYS is the least prevalent (4.7%).
The following chunk shows the exact call used to generate the
precomputed results stored in
inst/extdata/results_bin.rds.
The first three observed eigenvalues exceed their permutation-based 95th- percentile reference values, supporting retention of a K* = 3-dimensional MCA subspace. These three dimensions account for approximately 48% of total inertia.
Median principal angles are 2.77°, 6.94°, and 15.46° for Dimensions 1–3, all well below the 20° threshold. Tucker congruence coefficients range from phi = 0.978 to phi = 0.992. All three dimensions pass the dual criterion, yielding K* = 3.
Variance weights are 0.4345, 0.2979, and 0.2676 for Dimensions 1–3. ALSI values range from 0.040 to 1.625 (M = 0.373, Mdn = 0.368).
This example illustrates the alsi_workflow_ordinal()
pipeline using the ten Extraversion items (E1–E10) from the Big Five
Inventory (BFI; N = 500).
BFI <- read.csv(system.file("extdata",
"BFI_Original_Ordinal_N500.csv",
package = "SEPA"))
items <- paste0("E", 1:10)
reversed_items <- c("E2", "E4", "E6", "E8", "E10")
head(BFI[, items])freq_table <- sapply(BFI[, items], function(x) table(factor(x, 1:5)))
round(100 * freq_table / nrow(BFI), 1)Response frequencies are well distributed across the 1–5 scale for all ten items, with no category falling below the 2% rare-category threshold.
The first four observed eigenvalues exceed their 95th-percentile reference values, supporting an initial K_PA = 4-dimensional solution.
Dimensions 1–3 satisfy both stability thresholds simultaneously. Dimension 4 fails the angle criterion (median theta = 24.39° > 20°), yielding K* = 3. All 1,000 bootstrap resamples converged successfully (skipped = 0).
print(results_ord)
cat("oALSI summary:\n")
print(summary(results_ord$ALSI_index))
cat("\noALSI (z-scored) summary:\n")
print(summary(results_ord$ALSI_z))Variance weights for K* = 3 are 0.4815, 0.3307, and 0.1878. The ordinal ALSI distribution is slightly negatively skewed, ranging from -0.014 to 0.025 (Mdn = -0.001, M = 0.000).
This example illustrates the calsi_workflow() pipeline
using N = 900 individuals assessed on p = 9 domain scores from the
WAIS-IV and WMS-IV cognitive batteries.
wawm4 <- read.csv(system.file("extdata", "wawm4.csv", package = "SEPA"))
domains <- c("VC", "PR", "WO", "PS", "IM", "DM", "VWM", "VM", "AM")
X <- wawm4[, domains]
cat("N =", nrow(X), " p =", ncol(X), "\n")Domain means ranged from approximately 99 to 101 and standard
deviations from approximately 14 to 16, consistent with the standard
score metric (normative M = 100, SD = 15). Row-mean-centering is applied
internally by calsi_workflow().
Horn’s parallel analysis supported retention of four dimensions, accounting for approximately 78.28% of total variance in the row-mean-centered solution.
All four dimensions satisfy both stability thresholds (median principal angles 0.13°-10.37°, all < 20°; Tucker congruence 0.987-0.999, all >= 0.95), yielding K* = 4.
Variance weights for K* = 4 are 0.3833, 0.2481, 0.2222, and 0.1465. cALSI values range from 1.58 to 32.53 (M = 11.81, Mdn = 10.96, SD = 5.09). Processing Speed (PS, 21.5%) contributes most to the retained profile subspace.
These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.