Calculating Quartile Deviation
To calculate the quartile deviation of a given data set, follow these steps:

Step 1: Find the Quartiles
- First, arrange the data in ascending order: 1, 3, 5, 7, 9, 11, 13, 15.
- Next, find the first quartile (Q1) and the third quartile (Q3).
- Q1 = (n+1)/4th term = (8+1)/4th term = 2.25th term
- Q3 = 3*(n+1)/4th term = 3*(8+1)/4th term = 6.75th term
- The 2.25th term is between the 2nd and 3rd term, so Q1 = (3+5)/2 = 4.
- The 6.75th term is between the 6th and 7th term, so Q3 = (11+13)/2 = 12.

Step 2: Calculate Quartile Deviation
- Quartile deviation = (Q3 - Q1)/2 = (12 - 4)/2 = 4.
Therefore, the quartile deviation of the data 1, 3, 5, 7, 9, 11, 13, 15 is 4. Quartile deviation is a measure of statistical dispersion that is based on the difference between the third and first quartiles, divided by 2. It gives an indication of how spread out the middle 50% of the data is.