Q.D. = Q3 – Q1 / 2
So, to calculate Quartile deviation, you need to first find out Q1, then the second step is to find Q3 and then make a difference of both, and the final step is to divide by 2. This is one of the best methods of dispersion for open-ended data.
Why do we calculate quartile deviation?
The Quartile Deviation is a simple way to estimate the spread of a distribution about a measure of its central tendency (usually the mean). So, it gives you an idea about the range within which the central 50% of your sample data lies.
What is the formula for Q1 and Q3?
Formula for Lower quartile (Q1) = N + 1 multiplied by (1) divided by (4) Formula for Middle quartile (Q2) = N + 1 multiplied by (2) divided by (4) Formula for Upper quartile (Q3) = N + 1 multiplied by (3) divided by (4)
