interkwartielafstand

The interkwartielafstand, or interquartile range (IQR), is a statistical measure used to describe the spread or dispersion of a dataset. It is defined as the difference between the upper quartile (Q3) and the lower quartile (Q1). These quartiles divide a ranked dataset into four equal parts. The lower quartile Q1 marks the 25th percentile, meaning 25% of the data points lie below this value. The upper quartile Q3 marks the 75th percentile.

Unlike the range, which considers the extreme minimum and maximum values, the IQR focuses on the middle 50% of the data. This characteristic makes it a robust measure of variability, as it is not influenced by potential outliers or extreme values that can skew the interpretation. A larger IQR indicates a greater spread in the central portion of the dataset, while a smaller IQR suggests the data is more tightly clustered around the median.

The primary use of the IQR is in descriptive statistics, often visualized in box plots, where it forms the body of the box. It is particularly useful for comparing the distribution of different datasets. The IQR can also be used in outlier detection; data points that fall more than 1.5 times the IQR below Q1 or above Q3 are often considered potential outliers. Due to its resistance to extreme values, the interkwartielafstand is a valuable tool for understanding the core trend within a dataset, providing a clearer picture than the full range when data contains anomalies.