How to work out semi interquartile range in stats

Answer 1

To calculate the semi-interquartile range, also known as the semi-interquartile deviation, you first need to calculate the interquartile range (IQR).

1. First, arrange your data in ascending order.
2. Calculate the median (Q2) of your data set.
3. Find the median of the lower half of the data, called Q1.
4. Find the median of the upper half of the data, called Q3.
5. Calculate the interquartile range (IQR) by subtracting Q1 from Q3: IQR = Q3 - Q1.

Once you have calculated the interquartile range, the semi-interquartile range is simply half of the IQR:

Semi-Interquartile Range = IQR/2

This measure is more robust to extreme values in the data compared to the full range and can give you a better idea of the spread of the central portion of your data set.