Glossary and quick-start checklist

tidyILD authors

2026-02-11

Glossary of main functions

Function Purpose
[ild_prepare()] Turn a data frame into an ILD object: parse time, sort, add .ild_* columns and spacing metadata.
[ild_summary()] One-shot summary: n persons, n observations, time range, spacing stats, gaps.
[ild_center()] Within-between decomposition: add _bp (person mean) and _wp (within-person) columns.
[ild_lag()] Spacing-aware lags: index, gap_aware, or time_window with a resolution rule.
[ild_check_lags()] Audit lag columns: count valid vs invalid (e.g. beyond max_gap).
[ild_spacing_class()] Classify spacing as “regular-ish” or “irregular-ish” (overridable).
[ild_missing_pattern()] Tabular and (via [ild_plot()] type "missingness") heatmap of missingness.
[ild_lme()] Fit mixed-effects model: lmer (no AR) or nlme with AR1/CAR1.
[ild_diagnostics()] Residual ACF, residuals vs fitted/time, Q-Q; optional AR parameter.
[ild_plot()] Trajectory, heatmap, gaps, missingness, fitted vs observed, residual ACF.
[ild_simulate()] Simulate simple ILD for examples and tests.

Quick-start checklist

  1. Prepare: x <- ild_prepare(data, id = "id", time = "time", gap_threshold = ...)
  2. Inspect: ild_summary(x), ild_plot(x, type = "gaps"), ild_plot(x, type = "missingness")
  3. Center: x <- ild_center(x, var1, var2) (adds _bp and _wp)
  4. Lag: x <- ild_lag(x, var1, mode = "gap_aware", max_gap = ...) or mode = "time_window", window = ...
  5. Check lags (optional): ild_check_lags(x, lag_vars = c("var1_lag1"))
  6. Fit: fit <- ild_lme(formula, data = x, ar1 = TRUE) (or ar1 = FALSE)
  7. Diagnose: ild_diagnostics(fit) and ild_plot(fit, type = "fitted"), type = "residual_acf"

Comparison with generic workflows

Task Generic R tidyILD
Time structure Manual sort, manual lags, no gap checks [ild_prepare()] + [ild_lag()] with gap or time-window rules
Within-between Manual person means, ad hoc naming [ild_center()] with consistent _bp/_wp
Residual correlation nlme syntax heavy; easy to mis-specify [ild_lme(ar1 = TRUE)] with auto or override AR1/CAR1
Lag validity Often unchecked [ild_check_lags()], gap_aware and time_window modes

Same goals, less code and fewer silent errors.