ELISA Cutoff Index
Calculate a blank-corrected ELISA cutoff index using the supplied assay cutoff.
Description
ELISA indices express a blank-corrected sample signal relative to a blank-corrected cutoff.
ELISA indices express a blank-corrected sample signal relative to a blank-corrected cutoff. The supplied cutoff controls the scale and decision threshold.
The tool returns correctedOd (corrected od); cutoffIndex (cutoff index); aboveCutoff (above cutoff). Input measurements and model parameters are supplied by the caller; the tool computes the stated summary rather than acquiring those measurements.
When to use ELISA Cutoff Index
Use ELISA Cutoff Index when you already have sampleOd, blankOd, cutoffOd, positiveIndexCutoff and want correctedOd, cutoffIndex, aboveCutoff. This is useful for checking a supplied calculation, documenting a measurement convention, or comparing observations prepared on the same basis.
How to use ELISA Cutoff Index and understand its results
- Enter sampleOd, blankOd, cutoffOd, positiveIndexCutoff using the field table below. Match the units, ordering and data boundaries described in the calculation.
- Run the tool after checking the stated bounds and matching paired observations or categories. A malformed request gives a tool error rather than a usable measurement.
- Read correctedOd, cutoffIndex, aboveCutoff. Use the calculation and interpretation below to distinguish amounts, ratios, signs and decision flags where applicable.
- Review the supplied parameters and assumptions before using the result in a report or comparing it with another observation.
| Input field | Meaning | Value type and bounds | Requirement |
|---|---|---|---|
| sampleOd | Sample od | number | Required |
| blankOd | Blank od | number | Required |
| cutoffOd | Cutoff od | number | Required |
| positiveIndexCutoff | Positive index cutoff | number | Required |
Require nonnegative optical densities and a cutoff above the blank. Classify an index at or above the positive caller criterion as meeting the threshold.
corrected sample = max(0, sampleOD − blankOD); index = corrected sample/(cutoffOD − blankOD) The symbols refer to the supplied quantities or generated values described above; unit conversions and comparison boundaries follow the stated implementation.
{
"input": {
"sampleOd": 0.6,
"blankOd": 0.1,
"cutoffOd": 0.5,
"positiveIndexCutoff": 1
},
"output": {
"correctedOd": 0.5,
"cutoffIndex": 1.25,
"aboveCutoff": true
}
}Limitations and assumptions
Negative blank-corrected sample signals are clipped to zero. Assay calibration, repeat testing and diagnostic interpretation remain external.
Numerical inputs must be finite. The tool checks its declared input shape and calculation constraints; those checks do not verify the quality, calibration or representativeness of the supplied observations.
Alternative or Complementary methods
Western Band Pattern Match: Compare western-blot band observations with caller-defined required and forbidden assay patterns. Parasite Ct Copy Number: Back-calculate parasite copy concentration from a supplied Ct calibration and extraction volumes.
Methodological background: DPDx: diagnostic procedures.1
References
-
DPDx: diagnostic procedures — Centers for Disease Control and Prevention
Similar or alternative tools
- Western Band Pattern Match
Compare western-blot band observations with caller-defined required and forbidden assay patterns.
- Parasite Ct Copy Number
Back-calculate parasite copy concentration from a supplied Ct calibration and extraction volumes.