Range Calculator
Free range calculator. Range, semi-range, IQR, interdecile range, interpercentile range, relative ra
Why This Statistical Analysis Matters
Why: Statistical calculator for analysis.
How: Enter inputs and compute results.
Range, IQR, Interdecile Range, Relative Range
Compute range, semi-range, IQR, interdecile range, interpercentile range, relative range, coefficient of range, and range rule of SD.
Real-World Scenarios โ Click to Load
Data & Percentile Bounds
Data Strip with Range/IQR/IDR Highlighted
Red: below D1 or above D9; Amber: D1โQ1 or Q3โD9; Blue: Q1โQ3 (IQR).
Range Measures Comparison
Key Measures Overview
Calculation Breakdown
For educational and informational purposes only. Verify with a qualified professional.
Key Takeaways
- โข Range = Max โ Min โ simplest measure of spread, sensitive to outliers
- โข Semi-Range (Midrange) = (Max + Min) / 2 โ midpoint of the range
- โข IQR = Q3 โ Q1 โ spread of middle 50%, robust to outliers
- โข Interdecile Range = D9 โ D1 โ spread of middle 80%, more robust than range
- โข Relative Range = (Range / Mean) ร 100% โ scale-invariant, like CV but for range
- โข Coefficient of Range = (Max โ Min) / (Max + Min) โ dimensionless [0, 1]
- โข Range Rule of SD: ฯ โ Range / 4 โ rough estimate for normal data
Did You Know?
Expert Tips
When to Use Range
Use range for quick summaries. Prefer IQR or interdecile when outliers exist.
Custom Percentiles
Set P5โP95 for middle 90%, or P10โP90 for middle 80%. Customize to your needs.
Coefficient of Range
Dimensionless; compare spread across datasets with different units or scales.
Range Rule
ฯ โ Range/4 works best for normal data with n > 15. Rough estimate only.
Range Measures Comparison
| Measure | Formula | Robustness | Use Case |
|---|---|---|---|
| Range | Max โ Min | Low (sensitive to outliers) | Quick summary |
| Semi-Range | (Max + Min) / 2 | Low | Center of range |
| IQR | Q3 โ Q1 | High | Middle 50% spread |
| Interdecile | D9 โ D1 | High | Middle 80% spread |
| Coefficient | (MaxโMin)/(Max+Min) | Low | Compare across scales |
Frequently Asked Questions
Why is range sensitive to outliers?
Range uses only Min and Max. One extreme value can dramatically increase the range.
What is the interdecile range?
D9 โ D1. Middle 80% of data. More robust than range when extremes exist.
When to use IQR vs range?
Use IQR for skewed data or when outliers exist. Range is fine for quick summaries of clean data.
What is the coefficient of range?
(MaxโMin)/(Max+Min). Dimensionless; range [0,1]. Useful for comparing across scales.
What is the range rule of SD?
ฯ โ Range/4. Rough estimate for normal data. Useful when n is large and SD is unavailable.
What is relative range?
Range/Mean ร 100%. Scale-invariant; like CV but for range.
How do I interpret the data strip chart?
Red = below D1 or above D9 (outer 20%); Amber = D1โQ1 or Q3โD9; Blue = Q1โQ3 (IQR, middle 50%).
Can I use custom percentiles?
Yes. Set lower and upper percentiles (e.g., 5 and 95) for interpercentile range of middle 90%.
Range by the Numbers
Formulas Reference
Range = Max โ Min
Semi-Range (Midrange) = (Max + Min) / 2
IQR = Q3 โ Q1
Interdecile Range = D9 โ D1
Relative Range = (Range / Mean) ร 100%
Coefficient of Range = (Max โ Min) / (Max + Min)
Range Rule of SD: ฯ โ Range / 4
Rough estimate for normal data
Applications
Quality Control
Range and IQR monitor process variation. Coefficient of range compares across products.
Finance
Stock price ranges, volatility. Interdecile range for robust return analysis.
Healthcare
Lab value ranges. IQR for robust reference intervals.
Education
Score ranges, grade distributions. IQR for robust spread comparisons.
Official Data Sources
Disclaimer: Range is sensitive to outliers. For skewed data, prefer IQR or interdecile range. Range rule of SD is a rough estimate only.
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