There are various ways to compute percentiles and statistical programs use different methods by default. I would prefer that we do like R and provide multiple options for the type of percentile computation. See http://stat.ethz.ch/R-manual/R-patched/library/stats/html/quantile.html
Patrick -----Original Message----- From: venkatesha murthy [mailto:venkateshamurth...@gmail.com] Sent: Wednesday, May 21, 2014 3:18 PM To: dev@commons.apache.org Subject: [MATH-1120] Needed opinion about support on variations in percentile calculation Hi All, The existing Percentile class calculates the percentile based on the quantile position of the array fixed as p * (N+1)/100 for a pth Percentile on an Array of size N. However if we were to add these numbers in MS Excel to calculate the percentile it provides a different result and closely resembeles the formula [p*(N-1)/100]+1. Its imperative at times to match the computations to a standard spreadsheet calculations or to a standard tool; which is why i request for allowing the quantile position to be customized. Infact even the kth selection used can also be refactored as a strategy(than as a private methods) as a further step. So if atleast the Percentile class were to allow the quantile position to be customized in the sub classes; then the end user may be helped in providing the formula of their choice. The most minimal change i am proposing here is to just make the quantile position setting as a protected method and i have attached a possible patch in [MATH-1120] <https://issues.apache.org/jira/browse/MATH-1120>. Request all to opinionate on this thanks venkat --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
