If a candidate scores 70th percentile in a section , it means that 70% of the test takers have scored less than the candidate.
All candidates who have taken the pH test in the previous two years are considered for percentile calculation. In the event of there being a change in the test format on a date which is less than 2 years in the past, then the percentile is calculated from the day on which the test format has changed.
pH test percentile is dynamic as it changes after every pH Test (with candidates who took the test more than 2 years ago getting dropped and candidates who took the test recently getting added to the list for calculating the pH Test Percentile).
However, majority of the times companies see a different score as the same is customized for each company based on the job role and skills required. The analytics and methodology used is proprietary to eLitmus and is evolved continuously. You may refer to following link to get more insights