Class frequency
Topic: Economic Data: Census, NSS, Surveys and Statistical Tools · NCERT: Class 11, Ch 3 "Organisation of Data"; Class 11, Ch 8 "Use of Statistical Tools"
Meaning
Class frequency is the number of observations that fall in a particular class of a frequency distribution. It is usually counted with tally marks, which are strokes drawn in groups of five to make counting easy. The class frequencies of all classes add up to the total number of observations.
Example
In NCERT's table of maths marks for 100 students, the 50-60 class has a class frequency of 23. That means 23 students scored between 50 and 60. The 40-50 class has 21 students and the 60-70 class has 19.
Don't confuse with
- Relative frequency: this is class frequency divided by the total, shown as a share. Together the 40-70 band has 21 + 23 + 19 = 63 of 100 students, a relative frequency of 63%.
Related concepts
- Raw data
- Classification
- Chronological classification
- Spatial classification
- Qualitative classification
- Quantitative classification
- Attribute
- Continuous variable
- Discrete variable
- Frequency