This section outlines the concept of interquartile range (IQR) and interdecile range. These measures provide valuable insights into the spread and variability of a dataset by looking at the spread of data points.
Interquartile Range (IQR)
The interquartile range (IQR) is a measure of spread. It quantifies the spread of the middle 50% of the data. It is calculated as the difference between the upper quartile (Q3) and the lower quartile (Q1):
IQR = Q3−Q1
In simpler terms, the IQR gives us the range in which the middle 50% of the data values lie. It is resistant to outliers, making it particularly useful for describing the variability of skewed distributions.
Interdecile Range (IQR)
The interdecile range provides insights into the spread of data across broader percentiles. While the interquartile range focuses on the middle 50% of the data, the interdecile range extends this concept to cover a broader spectrum. It measures the spread between the 10th percentile (P10) and the 90th percentile (P90):
Interdecile Range=P90−P10
The interdecile range is useful for understanding the dispersion of data across a wider range of percentiles, giving a more comprehensive view of variability beyond the middle 50%.