Functional Item Scale Offset Tool

Description

Apply an explicitly supplied affine research item crosswalk without validating scale equivalence.

Movement research distinguishes elapsed time, active time, cycle phase, measured force, and assessment-score conventions. Normalizing or remapping these quantities can help compare records when their units and definitions agree. A local arithmetic term does not by itself validate a functional assessment or an exercise program.

Apply an explicitly supplied affine research item crosswalk without validating scale equivalence.

When to use this tool

Use Functional Item Scale Offset when you need this motion, timing, force, annotation, or score-mapping component for supplied research records.

How to use the tool and how it works

Enter score, sourceLower, targetLower, scaleFactor. Use the units and conventions below.
Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
Read mappedScore. Use the output convention below.

Require nonzero scaleFactor and return mappedScore=targetLower+(score-sourceLower)*scaleFactor.^[1]

Input field	Meaning and units	Accepted input
score	Score	Required. Finite number.
sourceLower	Source Lower	Required. Finite number.
targetLower	Target Lower	Required. Finite number.
scaleFactor	Scale Factor	Required. Finite number.

Output field	Interpretation	Returned shape
mappedScore	Mapped Score	Required. Finite number.

json

{
  "input": {
    "score": 3,
    "sourceLower": 1,
    "targetLower": 0,
    "scaleFactor": 2
  },
  "output": {
    "mappedScore": 4
  }
}

Limitations and assumptions

A negative factor reverses direction and scores are not restricted to a scale range. This affine mapping does not validate equivalence between assessment instruments or measurement units.
Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Signed zero is exported as zero.

Alternative or Complementary methods

Use the intended assessment or motion-analysis protocol with verified timing, units, and event annotations. A complete interpretation needs the relevant measurement properties and task context beyond this local calculation.

References

Calculation and input contract: physiotherapy/functional-item-scale-offset — tool.io

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