Cumulative frequency
Also called: Cf · Topic: Geographical Data: Sources, Compilation and Processing · NCERT: Class 12, Ch 1 "Data - Its Source and Compilation"; Class 12, Ch 4 "Spatial Information Technology"
Meaning
Cumulative frequency (Cf) is a running total of frequencies. You add each class's frequency to the frequencies of all the classes before it. It tells you how many observations lie below a value (the "less than" type) or above a value (the "more than" type). In the less-than type, the last Cf always equals N, the total number of items. Plotting cumulative frequencies gives a curve called an ogive.
Example
In a set of 60 students' geography marks, the cumulative frequency shows that 27 students scored under 50 and 45 scored under 70. The final running total is 60, which equals all the students.
Don't confuse with
- Frequency: frequency is the count in one class only. Cumulative frequency adds up all classes so far.
Related concepts
- Grouping of data
- Class interval
- Tally marks
- Frequency distribution
- Exclusive method
- Inclusive method
- Frequency polygon
- Ogive