This document discusses various statistical methods for measuring central tendency and dispersion in data sets. It defines average or mean as representing the central part of a group. Dispersion is defined as the extent to which individual data points vary within a distribution. Methods for measuring dispersion described include range, quartile deviation, average deviation, and standard deviation. Standard deviation is specifically defined as a measure of how widely values are dispersed from the average value.

1. NAGESHA K
MANASA GANGOTHRI

2. 1) Mathematical Method
2) Graphic Method

3. Average
Average is basically the part of
the group and it is going to
represent the group of avrage .
E.g: In a class marks out of 10 in
english sbuject of 5 students.
2,5,6,8,4

4. Dispersion
Dispersion is the measure of
extent to which individual
items can vary
Or which a distribution is
stretched .

6. Range : It is a simplest method of studing
dispersion.
Range is the difference between
the Largest value and the smallest value of a
series .
Range = L – S
example :
In a class marks out of 50 in maths subject
of 6 students
Maths = 15, 20, 30, 18, 50, 45.
where, L=50, S=15.
Range = 50 – 15 R = 35

7. Quartile Deviation :
It is based on the upper quartile and
the lower quartile .
The difference upper quartile and lower
quartile is called as “Inter Quartile
range”
The difference upper quartile and lower
quartile divided by 2 is called Semi Inter
Quartlie or the Quartile deviation.

9. Average Deviation
Average Deviation is the
distance between each
value in the data set that
data set’s are mean or
median or mode.

11. Standard Deviation
The Standard Deviation indicates S.D
and aslo represented by the greek
letter sigma .
S.D = It is a measure that is used to
quantify the amount of dispersion of
a set of data values
And how much the data is spread
out around the mean or average.