Quartile in Statistics

Introduction to quartile
Calculating quartile
Quartile deviation

1. EDUCATIONAL STATISTICS
QUARTILE
Dr. Hina Jalal
[email protected]

2. IN STATISTICS, A QUARTILE ISA TYPE OF QUANTILE WHICH
DIVIDES THE NUMBER OF DATA POINTS INTO FOUR PARTS,
OR QUARTERS, OF MORE -OR-LESS EQUAL SIZE
Dr. Hina Jalal ([email protected])

3. 1.First quartile: 25% from smallest to
largest of numbers
2.Second quartile: between 25.1% and
50% (till median)
3.Third quartile: 51% to 75% (above the
median)
4.Fourth quartile: 25% of largest numbers
Dr. Hina Jalal ([email protected])

4. DIVISION OF QUARTILE
Dr. Hina Jalal ([email protected])

5. CALCULATING LOWER, MIDDLE, & UPPER QUARTILE
Q
1= [(n+1)/4]thitem
Q
2= [(n+1)/2]thitem
Q
3= [3(n+1)/4]thitem
Hence, the formula for quartile can be given by;
Where, Qr is the r
th
quartile
l
1is the lower limit
l
2is the upper limit
f is the frequency
c is the cumulative frequency of the class preceding the quartile
class.
Dr. Hina Jalal ([email protected])

6. QUARTILE FOR GROUPED DATA
Dr. Hina Jalal ([email protected])

7. Example 1
Dr. Hina Jalal ([email protected])

8. Example 2
Dr. Hina Jalal ([email protected])

9. Example 3
Dr. Hina Jalal ([email protected])

10. QUARTILE DEVIATION
You have learned aboutstandard deviationin statistics. Quartile deviationis defined as half
of the distance between the third and the first quartile. It is also calledSemi Interquartile
range. If Q
1is the first quartile and Q
3is the third quartile, then the formula for deviation is
given by;
Quartile deviation = (Q
3-Q
1)/2
Dr. Hina Jalal ([email protected])

11. INTERQUARTILE RANGE
Theinterquartile range (IQR)is the difference between the upper and lower quartile of a
given data set and is also called amidspread. It is a measure of statistical distribution, which
is equal to the difference between the upper and lower quartiles. Also, it is a calculation of
variation while dividing a data set into quartiles. If Q
1is the first quartile and Q
3is the third
quartile, then the IQR formula is given by;
IQR = Q
3–Q
1
Dr. Hina Jalal ([email protected])

12. Dr. Hina Jalal
@AksEAina ([email protected])