Ogive
Also called: Cumulative frequency curve · Topic: Geographical Data: Sources, Compilation and Processing · NCERT: Class 12, Ch 1 "Data - Its Source and Compilation"
Meaning
An ogive is a curve made by plotting cumulative frequencies, which are running totals of frequencies. There are two kinds. The less-than ogive plots totals against the upper limits of the classes, so it rises. The more-than ogive plots totals against the lower limits, so it falls. The point where the two curves cross gives the median, the middle value of the data.
Example
In NCERT's data of 60 students' geography scores, 27 students scored under 50 and 45 scored under 70. These running totals are points on the less-than ogive, which ends at 60, the total number of students.
Don't confuse with
- Frequency polygon: plots the simple frequency of each class. An ogive never plots simple frequency, only cumulative frequency.
Related concepts
- Grouping of data
- Class interval
- Tally marks
- Frequency distribution
- Cumulative frequency
- Exclusive method
- Inclusive method
- Frequency polygon