Impute left-censored (below-LOD) toxicology values

Forensic assays left-censor: results below the limit of detection are reported only as "< LOD". Naive deletion or zero-filling biases summaries. This applies a documented simple-substitution rule to the censored entries; for regression on censored data prefer morie_horowitz_censored_regression.

Usage

morie_tox_left_censor_impute(values, lod, method = "half")

Arguments

values

Numeric vector of measured concentrations; censored entries are NA (or values below lod).

lod

Limit of detection (scalar > 0). Entries NA or < lod are treated as left-censored.

method

"half" (LOD/2, the common default), "sqrt2" (LOD/sqrt(2), for moderate censoring), or "lod" (substitute LOD).

Value

A list with the imputed vector, a logical censored mask, and the fraction_censored.

Examples

morie_tox_left_censor_impute(c(0.4, NA, 0.9, 0.02), lod = 0.05)$imputed
#> [1] 0.400 0.025 0.900 0.025