# stats 200

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CHAPTER 2
Measures of Central Tendency And Dispersion

2.1 Introduction

In this chapter we will study various types of data, methods of data collection , data representation and measures of central tendency.

First question is ‘What is data”? Data is a set of something that we want to know about the object or objects under study. For example if we want to study performance of students in an examination, set of marks obtained by students will be our data.

Data can be gathered by different methods which we will study in detail in this chapter. After collection of data we need to classify the data to know, as in above case, the performance of the students and analyze that data to arrive at certain conclusions and finally we need to make presentation of our studies to the concerned authorities. Data representation usually precedes data analysis as we come to know various trends within the data through data representation.

In mathematics, an average, or central tendency of a data set refers to a measure of the middle or expected value of the data set. There are many different types of averages that can be chosen as a measurement of the central tendency of the data items. The most common method is the arithmetic mean, but the other types of averages such as median, mode, geometric mean, harmonic mean etc are also useful in applicable situations.