SSEP N20 Calculator

Actual sampled peak latency for independently identified SSEP N20, not response onset. Supplied component-specific window, baseline, stimulus zero, artifact rejection and polarity independently established; ties retained, no norm/diagnosis or sub-sample interpolation.

Description

N20 is an identified negative component of a somatosensory evoked potential.

N20 is an identified negative component of a somatosensory evoked potential.^[1]

Finding the most negative supplied sample in a window does not independently recognize the component.

When to use SSEP N20 Calculator

Use this tool to calculate or review the supplied observations under the stated rules. Establish the assessment or recording protocol, units, instrument version and independently applicable reference or calibration.

How to use SSEP N20 Calculator and understand its results

Establish the assessment or recording protocol, units, instrument version and independently applicable reference or calibration.
Enter independentlyMeasuredStimulusRelativeTimesMs, independentlyMeasuredBaselineCorrectedAmplitudes, callerIdentifiedComponentWindowStartMs, callerIdentifiedComponentWindowEndMs, using the field meanings and rules below, then run the tool.
Read result.sampledPeakTime, result.sampledPeakAmplitude, result.tiedSampledPeakTimes. Use the units and sign conventions below.
Correct any reported input issue and run again. Before using a successful result, check the stated units, signs, reference scope and observation coverage.

Input field	Meaning	Value type	Requirement
independentlyMeasuredStimulusRelativeTimesMs	Independently measured stimulus relative times ms	list of number	Required
independentlyMeasuredBaselineCorrectedAmplitudes	Independently measured baseline corrected amplitudes	list of number	Required
callerIdentifiedComponentWindowStartMs	Caller identified component window start ms	number	Required
callerIdentifiedComponentWindowEndMs	Caller identified component window end ms	number	Required

Enter at least two aligned finite time and baseline-corrected amplitude samples with strictly increasing times. Supply an ordered component window; at least one sample must lie inside its inclusive boundaries. Select the largest negative-magnitude excursion inside that window; the winning polarity-adjusted amplitude must be strictly positive. Return the first tied peak time, its original signed amplitude and all exactly tied peak times. Time coordinates may be signed and no interpolation, filtering, baseline estimation, component recognition or onset detection is added.

indices={i:windowStart≤time_i≤windowEnd}; peak=max(-1×amplitude_i), peak>0; selectedTime=first time attaining peak

Use the matching field units and the exact boundary, ordering and reference rules above.

Output field	Meaning	Value type
result	Structured result; its nested fields below contain the actual calculation or selected reference	object
result.sampledPeakTime	Time in milliseconds of the first sample attaining the selected-polarity maximum inside the inclusive window	number
result.sampledPeakAmplitude	Original signed amplitude at that first selected peak; in the supplied recording amplitude unit	number
result.tiedSampledPeakTimes	All exactly tied selected peak times in milliseconds, preserving sample order	list

json

{
  "input": {
    "independentlyMeasuredStimulusRelativeTimesMs": [
      1,
      2,
      3,
      4
    ],
    "independentlyMeasuredBaselineCorrectedAmplitudes": [
      0,
      -2,
      -2,
      0
    ],
    "callerIdentifiedComponentWindowStartMs": 1,
    "callerIdentifiedComponentWindowEndMs": 4
  },
  "output": {
    "result": {
      "sampledPeakTime": 2,
      "sampledPeakAmplitude": -2,
      "tiedSampledPeakTimes": [
        2,
        3
      ]
    }
  }
}

Limitations and assumptions

Actual acquisition, assessment protocol, instrument version and calibration determine applicability. The tool does not examine a person, classify images, administer a questionnaire or choose diagnostic cutoffs.

Missing required fields, unknown fields, wrong types and violated rules return input issues. Numeric values and outputs must be finite. Lists and matrices must be dense, without missing cells. Numeric lists allow at most 10000 entries; ordinary string lists allow at most 128 strings of 128 UTF-16 units each; numeric matrices allow at most 128 rows and 128 columns, subject to narrower requirements above. Extremely large composite outputs are rejected.

Alternative or Complementary methods

For a related step, use VEP P100 Calculator: P100 is an identified component of a visual evoked-potential recording. For a complementary comparison, use ERP N170 Latency Calculator: N170 is an independently identified negative event-related-potential component.

References

SSEP N20 Calculator — tool.io

Similar or alternative tools

VEP P100 Calculator
P100 is an identified component of a visual evoked-potential recording.
ERP N170 Latency Calculator
N170 is an independently identified negative event-related-potential component.