VIDEO TUTORIAL: How to calculate Percentile Rank (for A/B testing)
Percent ranking answers what "% of values were less than Y." Kudos to @GrantSmith for the question.
This is useful for comparing test results in two populations. Imagine 67 respondents tested 75% or les whereas in group B 99 respondents scored 75% or less.
To calculate % rank, you calculate the rank and divide each rank by the count of values.
Here's the video tutorial on 3 different ways to calculate the result (using MagicETL, Analyzer and Dataset Views)