Re: st: RE: broken axis symbol?

[Constantine Daskalakis <c_daskalakis@entwhistle.jci.tju.edu>]

At 01:04 PM 5/14/03, Nick Cox wrote:
> As I recall, Darrell Huff in his 1954 book implied that axes
> which don't start at zero are deceitful. And I seem
> to remember my high-school science teachers saying the
> same thing in the 1960s and recommending a scale break.
> [snip]
>
> Nick
> n.j.cox@durham.ac.uk
I beg to differ on this one Nick.
I think being able to "break" the axis is a crucial feature in plots.

Suppose I want to plot the percent of adolescents who've ever used a 
computer in the US over the past 10 years (estimated from repeated 
cross-sectional samples). During that period, this proportion has gone up 
from about 70% or so to over 95%.

Y-axis is "% used computer" and X-axis is calendar time (years).

First, I don't want to plot on the log scale. Why would I?

Second, I don't want to waste three quarters of my graph area by using the 
full scale of the Y axis (i.e., 0-100%), when all my measurements are 
around 85-95%.

I can start my Y-axis at, say, 60%, but I think that's more misleading than 
starting at 0% and having a "break" to jump to, say, 60%.




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________________________________________________________________

Constantine Daskalakis, ScD
Assistant Professor,
Biostatistics Section, Thomas Jefferson University,
125 S. 9th St. #402, Philadelphia, PA 19107
   Tel: 215-955-5695
   Fax: 215-503-3804
   Email: c_daskalakis@mail.jci.tju.edu
   Webpage: http://www.kcc.tju.edu/Science/SharedFacilities/Biostatistics

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