In a recent issue of Significance, I discovered an interesting – and amuzing – figure, about some box & beard plot, in *Dr Fisher’s casebook: Beard the statistician in his den*.

In French, the box plot (introduced by John Tukey, not George Box, as discussed in a previous post) is popular under the name *boîte à moustaches *(box with a mustache, for a simple translation).

> set.seed(2) > x=rnorm(500) > boxplot(x,horizontal=TRUE,axes=FALSE) > axis(1)

I was wondering if it was possible to reproduce that Fisher’s style of box plot, with a beard (Ronald Fisher was famous for his beard). Technically, it is not complicated,

> boxplot(x,horizontal=TRUE,xlim=c(-1,1.3),axes=FALSE) > axis(1) > Q=quantile(x,c(.25,.75)) > y=cut(x[(x>=Q[1])&(x<=Q[2])],seq(Q[1],Q[2],length=11)) > tb=table(y) > u=seq(Q[1],Q[2],length=11) > umid=(u[1:10]+u[2:11])/2 > for(i in 1:10) segments(umid[i],1-.2,umid[i],1-.2-tb[i]/20,lwd=3)

Yes, I kept the mustaches here, but ploting a simple box, one could easily draw a goatee, or a chin strip

> rect(Q[1],1-.2,Q[2],1+.2) > segments(median(x),1-.2,median(x),1+.2,lwd=2)

The only problem, is that between the first and the third quartiles, the distribution is much more ‘*uniform*‘ than it might look on the figure in Significance. Unless, perhaps, if add more bars on the left of the first quartile, and on the right of the third one,

> du=diff(umid)[1] > y=cut(x,seq(Q[1]-du*8,Q[2]+du*8,length=11+16)) > tb=table(y) > u=seq(Q[1]-du*8,Q[2]+du*8,length=11+16) > umid=(u[1:26]+u[2:27])/2 > for(i in 1:8) segments(umid[i],1,umid[i],1-.2-tb[i]/20,lwd=3) > for(i in 19:26) segments(umid[i],1,umid[i],1-.2-tb[i]/20,lwd=3)

Of course, we can try to add a smile on that face, below the mustache,

> vu=seq(-2.5,2.5,by=.02) > vv=dnorm(vu) > lines(vu,1-vv*4,col="red",lty=2) > d=density(x,bw=.1) > lines(d$x,1-d$y*4,col="red")

So far, I am not convinced. I mean, it should be possible to add something on the box plot, to add more information. But I still wonder what… maybe using colors?

I really love your “boîtes-à-barbe” !

Very best,

Enrico

Your beard plot is nothing more than a violin plot !

indeed, there are connections (http://www.tandfonline.com/doi/abs/10.1080/00031305.1998.10480559) or also the bean plot (http://www.jstatsoft.org/v28/c01/paper)

Arthur –

why not convey density information through just differences in color, rather than shape? just track density to alpha. I would like to see that.

“why not convey density information through just differences in color?”

No good for printing and photocopying