Re: Percentile Scores

[John Darrington]

On Wed, Mar 22, 2023 at 10:46:13AM -0500, Alan Mead wrote:
> When I was a young analyst, someone asked if the percentiles I'd provided
> were calculated the "right way" or the "wrong way." Using the cumulative
> percents is the "wrong way" (obviously, for some values of "wrong").
> 
> The "right way" (for some values of "right" or "correct") calculates the
> percentile of the midpoint of the score category and will never be exactly 0
> nor exactly 100.

In PSPP you can choose any of 5 different ways to calculate percentiles, 
depending
on which you considere "correct".  See section 15.3 of the manual.
I think you will see a difference only when the data set is very small or when 
there
are a large number of tied scores.

J'