Comprehensive Calculator Guide
This calculator finds the value at a given percentile of your sorted data: the 90th percentile is a value about 90% of the data don’t exceed. For 6, 7, 15, 36, 39, 40, 41, 42, 43, 47, 49 it is 47. It works for any percentile or decile, interpolating between ranks as Excel does.
Percentiles
Position = (p ÷ 100) × (n − 1) + 1 in the sorted data, interpolating between neighbours. The 50th is the median, the 25th and 75th the quartiles; growth charts and test scores use percentiles.
How to Use
- Enter the data.
- Enter the percentile, 0 to 100.
- Press “Calculate” to see the value and its position.
Formula Used
Position = (p ÷ 100)(n − 1) + 1, then interpolate
Practical Examples
- Example 1
- 90th: 47.
- Example 2
- 30th of the marks: 80.5.
Important Tips
- Sort first.
- The 50th should equal the median.
- State the method.
Common Mistakes to Avoid
- Confusing percentile and percentile rank.
- Using p × n everywhere.
- Unsorted data.
Frequently Asked Questions
- 90th percentile?
- A value 90% don’t exceed.
- Vs percentile rank?
- A value vs a share.
- Deciles?
- The 10th, 20th … 90th.