Statistics function incorrectly computing median

[Ben Abbott]

On Jan 27, 2008, at 7:57 AM, Miguel Garcia-Blanco wrote:

>> I struggled quite a bit with #3. To be honest, I had little hope it
>> was working properly. The part below was added to obtain agreement
>> with R in several cases.
>>
>> --------------------------------------------
>> ----- from __quantile__.m, lines 92:96 -----
>> --------------------------------------------
>>  if (x(k(q)) <= 0.5)
>>    inv(k(q)) = v(find(dx == min(dx), 1, "first"));
>>  else
>>    inv(k(q)) = v(find(dx == min(dx), 1, "last"));
>>  endif
>> --------------------------------------------
>>
>> I'm skeptical that part should be there. Any idea on what the proper
>> algorithm for #3 might look like?
>
> I found the R help to be ambiguous, so I went to the SAS website and  
> found
> an appropriate help page
> (http://support.sas.com/onlinedoc/913/getDoc/en/statug.hlp/stdize_sect14.htm 
> ).
> I've crudely coded up SAS method PCTLDEF=2 and it seems to work (but  
> it's
> not in anyway optimised).
>
> -Miguel
> <quant3.m>

Thanks Miguel, you script was very helpful.

I've modified the algorithm to be consistent with the other cases, and  
the results remain consistent with yours.

I've attached the three new functions (__quantile__.m, quantile.m, &  
prctile.m), as well as the modified statistics.m.

If there are no other problems, I'll generate a patch.

Ben

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