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enter image description hereIf one achieves a score in the 99th percentile on an exam, is that score considered in the top 1% or 2%? How is percentile defined in statistics?

I read this somewhere: It’s top 2% - being in the x percentile doesn’t imply top (100-x) percent because the percentage getting exactly x is counted twice.

Is this correct?

user27343
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1 Answers1

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If you're in the 99th percentile, 99 percent of the population is below you, so you are in the top 1 percent.

Rory M. Tims
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  • I apologize. I accidentally edited your answer, but I needed to edit my question. Do you mind looking at it again? – user27343 May 09 '19 at 16:16
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    To build upon this answer, there are 100 percentiles, numbered from the 0th to the 99th. That is to say that the zeroth is above 0% of the population. There is no 100th percentile, even for the highest score on the exam, because it is not above itself. – Monty Harder May 09 '19 at 17:59
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    @MontyHarder Then this seems like a choice of standards - for example, on Wikipedia: "...the $P$-th percentile ($0 < P \leq 100$)...". In that case, the 100th percentile would be the top 1%, while the 99th would be the top 2%. – Ian May 09 '19 at 18:31
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    @Ian There are two different senses of the term "percentile". The second represents the 99 boundaries between the 100 groups of the first sense. The second sense is not used with the preposition "in"; one cannot be "in the 100th percentile" because there is nothing between the highest score and itself. I avoid using the second sense because it's just too confusing. – Monty Harder May 09 '19 at 19:16
  • Yes, but I'm pretty sure that generally percentile is considered top (100-x), because no one has scored in the 100th percentile in tests, (because it's not possible.) – Rory M. Tims May 10 '19 at 01:40