Interquartile Range Calculator
Calculate interquartile range (IQR), semi-IQR, midhinge, and coefficient of quartile deviation. Detect mild and extreme outliers using Tukey's fences with box plot visualization.
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IQR Calculator - Interquartile Range Calculator
Calculate the interquartile range (IQR) and related statistics for any dataset. Detect outliers, compute quartile deviation (semi-IQR), midhinge, and coefficient of quartile deviation with interactive box plot visualization.
What is Interquartile Range (IQR)?
The interquartile range (IQR) is a measure of statistical dispersion, representing the spread of the middle 50% of your data. Also called midspread, middle 50%, or H-spread, it's calculated as IQR = Q3 - Q1 (the difference between the 75th and 25th percentiles). IQR is robust to outliers, making it more reliable than range for skewed distributions.
IQR Formula
IQR = Q₃ - Q₁How to Calculate IQR
Applications of IQR
Outlier Detection
Identify unusual values in datasets using Tukey's fence method (1.5×IQR and 3×IQR rules).
Box Plot Creation
IQR defines the box in box plots, showing the middle 50% of data distribution.
Data Quality Assessment
Evaluate data spread and identify potential errors or anomalies in measurements.
Comparing Distributions
Compare variability across different groups or time periods using a robust measure.
Frequently Asked Questions
Quartile deviation, also known as semi-interquartile range, equals half the IQR (IQR ÷ 2). It provides a measure of dispersion that shows the average distance of Q1 and Q3 from the median, useful for symmetric distributions.