Page 96 - Kỷ yếu hội thảo khoa học lần thứ 12 - Công nghệ thông tin và Ứng dụng trong các lĩnh vực (CITA 2023)

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3 Basic Notions

In this section, we briefly present basic notions related to the representation of the
measure of central tendency and collective decision.

Types of Measure of Central Tendency

For comparison the condensation of data set, it is necessary to summarize the data set
in a single value. Such a value usually somewhere in the center and represent the
entire data set and hence it is called measure of central tendency or averages.

Definition 1. A value obtained by dividing the sum of all the observations by the
number of observations is called arithmetic mean or simply as the mean [6].

Let x 1, x 2 x n be the data values, then we have

(1)

where is a symbol representing the mean of the x i values.
If the data are grouped, with fi occurrences of the value xi for I
their mean is given by

(2)

where the numerator is the sum of all of the xi values and the denominator is the total
number of values.

th
Definition 2. A value obtained by the n root n
called geometric mean [6].

Let x 1, x 2 x n be the data values, then the geometric mean (GM) is defined as:

(3)

This can also be written as

Therefore,

(4)

where n = f 1 + f 2 n

CITA 2023 ISBN: 978-604-80-8083-9