Stata The Stata listserver
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

st: RE: pctile, xtile methods -- correction


From   [email protected]
To   [email protected]
Subject   st: RE: pctile, xtile methods -- correction
Date   Mon, 9 Jun 2003 08:42:45 -0400

I wrote
> 2. Possibly inaccurate percentiles
> ==================================
> 
> In the example above, the 7th percentile is 8.  But according to the
default
> method, x_7 should be given by the mean of x[6] and x[7] because P =
> _N*(7/100) = 7, the smallest index i > P is i = 8 and (i-1) = P.  This
> implies that x_p should be 7.5 for p = 7.


I should have written,

2. Possibly inaccurate percentiles
==================================

In the example above, the 7th percentile is 8.  But according to the default
method, x_7 should be given by the mean of x[7] and x[8] because
                                             ^        ^
P = _N*(7/100) = 7, the smallest index i > P is i = 8 and (i-1) = P.  This
implies that x_p should be 7.5 for p = 7.



Patrick Joly
[email protected]
[email protected]
*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/



© Copyright 1996–2024 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index