Searching for specific functions
1) I am not sure why you want the biased version but here are two ways to do this. Also if you have large enough sample size, it would not matter much. my.var1 <- function(x) mean( (x - mean(x))^2 ) my.var2 <- function(x) mean( x^2 - mean(x)^2 ) 2) Look at quantiles function. Your equation might correspond to one of the types given there. Regards, Adai
On Fri, 2005-09-30 at 10:46 +0200, Fabrizio Ferri Benedetti wrote:
Hello everybody (I'm new here) I am looking for 2 specific functions. The first one is a variance formula that does not divide by n-1 (I don't want the unbiased formula, that's it). In case it does not exist, how do I modify the default function code? Yes, a workaround would be to multiply the result by n-1 and then divide it by n, but I'd like to use a separate function, if possible. The other function I'm looking for it's a median formula like this one: http://www.faberitius.com/prototipo/gfx/clip_image002_0000.gif Where "Li" is the exact lower limit of the critical interval, "nb" is the number of cases that lie below the critical interval, "nd" the number of cases inside the mentioned interval, and "I" is the range of the interval itself. As you can see this formula calculates the median in categorical structured data. I couldn't find any functions that match the results done by hand... is there a contrib package out there that may help me? Should I program the function on my own? Thanks in advance, Fabrizio Ferri Benedetti