Detection Limit Imputation

Impute below-detection signals at a caller-selected fraction of the detection limit.

Description

Detection-limit imputation replaces measurements below a supplied limit with a chosen fraction of that limit.

Detection-limit imputation replaces measurements below a supplied limit with a chosen fraction of that limit. Equality stays unchanged.^[1]

Impute below-detection signals at a caller-selected fraction of the detection limit.

When to use Detection Limit Imputation

Use this tool to impute below-detection signals at a caller-selected fraction of the detection limit.

Prepare the measured profile, formula counts, upstream model outputs or caller-defined reference criteria requested. Keep paired entries aligned and units, sample basis and preprocessing consistent.

How to use Detection Limit Imputation and understand its results

Prepare the measured profile, formula counts, upstream model outputs or caller-defined reference criteria requested. Keep paired entries aligned and units, sample basis and preprocessing consistent.
Enter signals, limitOfDetection, imputationFraction using the field table and calculation rules, then run the tool.
Read imputedSignals, imputedIndexes. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
signals	Signals	list of number	Required
limitOfDetection	Limit of detection	number	Required
imputationFraction	Imputation fraction	number	Required

Enter nonnegative signals and limit and fraction from zero through one. Empty signals are allowed. Return modified signals and zero-based replaced indexes.

replacement=LOD×fraction; replace if signal<LOD

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
imputedSignals	Imputed signals	list of number
imputedIndexes	Imputed indexes	list of number

json

{
  "input": {
    "signals": [
      0,
      1,
      10
    ],
    "limitOfDetection": 2,
    "imputationFraction": 0.5
  },
  "output": {
    "imputedSignals": [
      1,
      1,
      10
    ],
    "imputedIndexes": [
      0,
      1
    ]
  }
}

Limitations and assumptions

The rule can lower or raise a replaced value. No missingness model, limit estimation or uncertainty correction is supplied.

Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Lists are limited to 100,000 entries; the rules above may require smaller limits. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Detection Limit: Estimate LOD from a measured standard concentration and target signal-to-noise ratio. For a complementary task, use Log2 Skew Transform: Apply a pseudocount log2 transform and measure dynamic-range compression.

References

Detection Limit Imputation — tool.io

Similar or alternative tools

Detection Limit
Estimate LOD from a measured standard concentration and target signal-to-noise ratio.
Log2 Skew Transform
Apply a pseudocount log2 transform and measure dynamic-range compression.