Description
Calculate a supplied right-minus-left reaching index and total.
Developmental records distinguish calendar age, supplied age corrections, observation states, assent and privacy choices. A corrected age can be negative under supplied assumptions, and a missing response differs from an observed zero. A display mask changes presentation without protecting the underlying record.
Calculate a supplied right-minus-left reaching index and total.
When to use this tool
Use Infant Reaching Laterality Index when you already have rightReaches, leftReaches and need to calculate a supplied right-minus-left reaching index and total.
How to use the tool and how it works
- Enter rightReaches, leftReaches. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read lateralityIndex, totalReaches. Use the output convention below.
Require nonnegative safe right/left counts with positive sum; return (right-left)/(right+left) and exact BigInt total exported safely.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| rightReaches | Right Reaches | Required. Safe integer; minimum 0. |
| leftReaches | Left Reaches | Required. Safe integer; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| lateralityIndex | (rightReaches-leftReaches)/(rightReaches+leftReaches), requiring a positive safe total. | Required. Finite number. |
| totalReaches | Total Reaches | Required. Safe integer. |
{
"input": {
"rightReaches": 6,
"leftReaches": 2
},
"output": {
"lateralityIndex": 0.5,
"totalReaches": 8
}
}Limitations and assumptions
- The index ranges -1..1 under the supplied count convention; unsafe totals are rejected. No reaches, handedness, motor development or clinical status is assessed.
- 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. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use the complete observation or assessment method, age convention and consent context. Review source records and data protection together; local counts, labels and geometric measurements do not establish development, diagnosis or appropriate support.
References
Similar or alternative tools
- Infant Age Correction Record Field
Subtract a supplied age correction from recorded chronological days.
- Developmental Task Completion Code
Distinguish unpresented, completed, declined and incomplete task records.