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Introduction
The scientific methods of collection of data, its classification and application to commerce and everyday life is called statistics. A list of some important terms as follows: (i) ungrouped data (ii) tabulation of data (iii) range (iv) frequency (v) frequency distribution (vi) tally (vii) inclusive type of grouped frequency distribution (viii) exclusive type of grouped frequency distribution (ix) lower limit and actual lower limit (x) upper limit and actual upper limit (xi) class size or class width (xii) class mark or class mid-interval (xiii) Variables (xiv) Continuous Variables (xv) Discrete Variables.
Graphical Representation
There are various methods of graphical representation of statistical data. In our study, we learn only two types. (i) Histogram (ii) Ogive or Cumulative Frequency Curve.
Cumulative Frequency Distribution
Cumulative frequency is obtained by adding the frequency of a class interval and the frequencies of the preceding intervals upto that class interval.
Ogive (Cumulative Frequency Curve)
A plot of the cumulative frequency against the upper class boundary with the points joined by line segments. Any continuous cumulative frequency curve, including a cumulative frequency polygon, is called an ogive. There are two ways of constructing an ogive or cumulative frequency curve. (Ogive is pronounced as O-jive). The curve is usually of 'S' shape.
Summary
1. Two types of graphical representation of data are the histogram and the ogive.
2. A histogram is a diagram which represents the class interval and frequency in the form of a rectangle.
3. An ogive or a cumulative frequency curve is a 's' shaped curve. Points on the ogive have abscissae as the actual upper / lower limits for 'less than' / more than curve and ordinates as the cumulative frequencies.
