Relative 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
Relative frequency shows what share of all observations falls in one class. It is the class frequency divided by the total frequency. It can be written as a proportion or as a percentage.
Relative frequency = class frequency ÷ total frequency
Raw counts can mislead when two groups have different totals. Relative frequencies fix this, because they put every group on the same scale of 0 to 1, or 0% to 100%.
Example
In NCERT's marks table for 100 students, 21 students scored 40-50, 23 scored 50-60 and 19 scored 60-70. That is 63 students, so the relative frequency of the 40-70 band is 63 ÷ 100 = 0.63, or 63%.
Don't confuse with
- Cumulative frequency: this adds up the frequencies of all classes up to a given class. Relative frequency looks at one class only.
Related concepts
- Raw data
- Classification
- Chronological classification
- Spatial classification
- Qualitative classification
- Quantitative classification
- Attribute
- Continuous variable
- Discrete variable
- Frequency