Explain the Aggregate Function ' PERCENTILE' in Tableau with Example?

In Tableau, the PERCENTILE function is an aggregate function used to calculate the value at a specified percentile of a numeric field within a specified context or group. Percentiles represent the values below which a certain percentage of the data falls.

The syntax for the PERCENTILE function in Tableau is as follows:

PERCENTILE(expression, percentile)

where the expression is the field or calculation for which you want to calculate the percentile, and percentile is the specific percentile value you want to calculate (expressed as a decimal or percentage).

Here's an example to demonstrate how to use the PERCENTILE function in Tableau:

Suppose you have a dataset that contains information about the scores of students in a test. You want to calculate the 75th percentile score to understand the performance of students at the upper quartile.

1. Open Tableau and connect to your dataset.
2. Drag the "Score" field to the Columns shelf.
3. In the Marks card, change the aggregation of the "Score" field to "Percentile" by clicking on the drop-down arrow next to the field and selecting "Percentile." This applies the PERCENTILE function to the "Score" field.
4. Tableau will prompt you to enter the percentile value. Enter 0.75 (or 75%) to calculate the 75th percentile.
5. Tableau will display the value at the 75th percentile in the view.

The result will show you the score below which 75% of the student scores fall. This helps you understand the performance of students at the upper quartile and provides insights into the distribution of scores.

The PERCENTILE function can also be used with other aggregate functions or in combination with other calculations to perform more complex analyses. For example, you can calculate the interquartile range (IQR) by subtracting the 25th percentile value from the 75th percentile value.

In summary, the PERCENTILE function in Tableau allows you to calculate the value at a specific percentile, providing insights into the distribution and relative position of data within a dataset.