Test HRV nonlinearity using surrogate data — test_gazepoint_hrv

Tests whether a nonlinear HRV statistic differs from surrogate RR/IBI sequences. This is a screening tool for evidence inconsistent with a simple linear stochastic null process. It does not prove deterministic chaos or diagnose any condition.

Usage

test_gazepoint_hrv_nonlinearity(
  dat,
  ibi_col = "IBI",
  group_cols = NULL,
  metric = c("sample_entropy", "approximate_entropy", "sd1_sd2_ratio"),
  n_surrogates = 99,
  surrogate_method = c("phase_randomized", "shuffle"),
  m = 2,
  r_multiplier = 0.2,
  statistic_fun = NULL,
  seed = NULL
)

Arguments

dat: A data frame containing IBI/RR intervals.
ibi_col: Numeric IBI/RR interval column.
group_cols: Optional grouping columns.
metric: Nonlinear statistic to test.
n_surrogates: Number of surrogate series per group.
surrogate_method: "phase_randomized" or "shuffle".
m: Embedding dimension for entropy metrics.
r_multiplier: Tolerance multiplier for entropy metrics.
statistic_fun: Optional custom statistic function accepting numeric x.
seed: Optional random seed.

Value

A list with overview, results, surrogate_statistics, and settings.