Percentiles
Topic: Economic Data: Census, NSS, Surveys and Statistical Tools · NCERT: Class 11, Ch 5 "Measures of Central Tendency"; Class 11, Ch 8 "Use of Statistical Tools"
Meaning
Percentiles are 99 values that divide ordered data into 100 equal parts. The k-th percentile (Pk) is the value below which k% of the items lie. They show where one item stands in the whole distribution. P50 is the median, the same as the fifth decile (D5) and the second quartile (Q2). P25 and P75 are the first and third quartiles. Percentiles belong to the family of partition values, which also includes quartiles (4 parts) and deciles (10 parts).
Example
If a student is at the 82nd percentile in an exam, 18% of the candidates scored higher. India's Household Consumption Expenditure Survey reports MPCE by fractile classes built in this way, from the bottom 5% to the top 5% of the population.
Don't confuse with
- Percentage: a percentage is a share of a total, such as 82% marks. A percentile is a rank position among all candidates.
Related concepts
- Measures of central tendency
- Arithmetic mean
- Weighted arithmetic mean
- Median
- Quartiles
- Decile
- Mode
- Bimodal and multimodal distribution
- Modal class
- Relative position of mean, median and mode