Define Ogive. What are its types? How do we construct all these?
At a time we are interested in knowing how many workers of a factory earn less than Rs. 700 per month or how many workers earn more than Rs. 1,000 per month, percentage of students who have failed etc. To answer these questions it is necessary to add the frequencies. When frequencies are added they are called cumulative frequencies. Then a table of cumulative frequencies is drawn, which when plotted on a graph paper is called the cumulative frequency curve or more popularly known as ‘Ogive’.
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There are two methods of constructing ogives:
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Less than Method: In the less than method we start with upper limits of class and go on adding the frequencies. When these frequencies are plotted we get a rising curve.
More than Method: Here, we start with lower limit and go on subtracting the frequencies of each class. When these frequencies are plotted a decreasing curve will be obtained.