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Dear AllStat,
There are different methods of ptiles computation implemented in different
software packages. As a result, for example 75th ptile computed in SPSS can
differ from 75th ptile computed in Excel etc.
I'd like to know what methods are used (e.g. based on parabolic estimation in
SAS).
I would be grateful for information about methods used (www, books etc.
where I could find more detailed math descrption, algorithms etc.).
Any idea what method of ptiles computation is in Excel (my colleague
tried to find this information from Microsoft but with no success).
Any criteria which method is the best?
Thank you in advance for your help,
Magda Les
P.S. Please, respond to me, not to the list
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