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| Introduction |
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| The scientific methods of collection of data, its classification and application to commerce and everyday life is called statistics. |
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| A set of observations is called a called a collection of data. These observations should possess some common characteristics. They are recorded and used for further study. The quantities such as age, height and number of students are called variables. |
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| A continuous variable can assume all values within a certain range, e.g., height, weight and age of persons are examples of continuous variables. |
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| A discrete variable can assume only integral values which can be counted. Number of pupils in a school, persons working in a factory are examples of discrete variables. |
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| A list of some important terms is given
below. |
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| (i) ungrouped data |
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| (ii) tabulation of data |
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| (iii) range |
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| (iv) frequency |
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| (v) frequency distribution |
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| (vi) tally |
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| (vii) inclusive type of grouped frequency distribution |
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| (viii) exclusive type of grouped frequency distribution |
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| (ix) lower limit and actual lower limit |
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| (x) upper limit and actual upper limit |
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| (xi) class size or class width |
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| (xii) class mark or class mid-interval. |
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