Quartile Deviation Calculator

An online quartile deviation calculator allows you to calculate quartile deviation (QD) for group data between the upper data value and lower data value of quartiles.

Result:

An online quartile deviation calculator allows you to calculate quartile deviation (QD) for group data between the upper data value and lower data value of quartiles.

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Formula :

QD = (Upper Quartile - Lower Quartile) / 2

Quartile deviation is based on the upper quartile (Q3) and the lower quartile (Q1) in a distribution. It is often regarded as semi interquartile range. To calculate quartile deviation first, arrange the given set of data in ascending order, find the center value and the find out the n/2+1 value. After that consider, first four values Q1 and last four values Q3. Find the median value for Q1 and Q3. At last subtract the value of Q3 with Q1 and divide it by 2. Use our online quartile deviation calculator for group data to calculate the first quartile, median value, third quartile and quartile deviation.

Example:

Calculate Quartile deviation for the following data set {1,3,2,6,8,9,10,5}

Solution:

Arranging the data in ascending order : 1, 2, 3, 5, 6, 8, 9, 10
First, we need to find median.
Here, median = 5 + 6 / 2
= 5.5
To find First/Upper Quartile,
find the mean of the last two values of the lower half data.
Lower half data = 1, 2, 3.
= 2 + 3 / 2
= 2.5
To find Third/Lower Quartile,
find the mean of the first two values of the upper half data.
Upper Half data = 8, 9, 10
= 8 + 9 / 2
= 17 / 2
= 8.5
To Find Quartile Deviation,
= (2.5 - 8.5)/2
= 3

Calculation of Quartile Deviation for group data is made easier here.

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