[Rd] stats::line() does not produce correct Tukey line when n mod 6 is 2 or 3

Serguei Sokol sokol at insa-toulouse.fr
Wed May 31 16:03:09 CEST 2017


Le 31/05/2017 à 15:40, Joris Meys a écrit :
> OTOH,
>
> > sapply(1:9, function(i){
> +   sum(dfr$time <= quantile(dfr$time, 1./3., type = i))
> + })
> [1] 8 8 6 6 6 6 8 6 6
>
> Only the default (type = 7) and the first two types give the result lines() gives now. I think there is plenty of reasons to give why any of the other 6 types 
> might be better suited in Tukey's method.
>
> So to my mind, chaning the definition of line() to give sensible output that is in accordance with the theory, does not imply any inconsistency with the 
> quantile definition in R. At least not with 6 out of the 9 different ones ;-)
Nice shot.
But OTOE (on the other end ;)
 > sapply(1:9, function(i){
+   sum(dfr$time >= quantile(dfr$time, 2./3., type = i))
+ })
[1] 8 8 8 8 6 6 8 6 6

Here "8" gains 5 votes against 4 for "6". There were two defector methods
that changed the point number and should be discarded. Which leaves us
with the score 3:4, still in favor of "6" but the default method should prevail
in my sens.

Serguei.



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