Thanks Nick & Allan. I have a lot of graphs I'm going to need to put
together for an appendix, and I was thinking that automating it with
Stata would give me the uniform appearance I wanted relatively
painlessly, except for that outlier problem. I'm pretty sure that in
almost all the cases a log scale would be confusing to the reader, so
I don't want to go with that.
Allan, I'll play with your suggestions and see if they do the trick
for me. Otherwise, it may be graphing in Excel, which does this
readily.
In the spirit of Nick's reminder on closing threads, I'll come back
and report if there's a solution that worked for me.
Thanks!
On 10/31/05, Nick Cox <[email protected]> wrote:
> Allan's main advice is to fit a regression line with
> an outlier and to show it on a graph together
> with all the other data.
>
> That's often a useful technique, but I read
> Timothy's discussion of line plots as wanting
> something quite different, namely
>
> * outlier off graph
>
> / \
> / \
> / \ lines on graph pointing to it
>
> I am sure that this is programmable, but I don't know an
> easy and general way for a user to do it.
>
> Likewise Allan's other suggestions do not seem to bear
> on this problem.
>
> Nick
> [email protected]
>
> Allan Reese (Cefas)
>
> > Hate to disagree with Nick, but Stata is well-designed for
> > intelligent graph editing. Timothy maybe needs to fiddle
> > with a few alternatives and work out what would show what he
> > intends. A log scale is one option but has many other implications.
> >
> > For example, it's straightforward in Stata to draw lines
> > with/without outliers. Other "point'n'click" packages don't
> > make this easy, so suppress the desire.
> >
> > fit y x
> > predict yhat1
> > fit y x if y<1000
> > predict yhat2
> > scatter y yhat1 yhat2 x if y<1000, connect(. l l) msym(o i i) sort
> >
> > Another simple trick is to copy one variable into several, so
> > subsets can be distinguished on the plot. You could automate
> > this (eg, using egen to save the max value of x), but I'd
> > usually do it as part of visual editing, for example to add
> > text labels to the points at the end of each line. It's
> > therefore feasible to draw a line for the data excluding the
> > outlier, and add a second line in different style pointing up
> > with a label at its end describing the outlier.
> >
> > This is the type of work where I'd draft commands in a DO
> > file so they are easily modified and re-run.
>
> Nick Cox
>
> > What you want is _not_ straightforward. I know no easy and also
> > general way of omitting a data point from a Stata graph and also
> > having it exert some offstage influence on the remainder of
> > the graph.
> >
> > In my experience, when people think they want something like
> > this using a logarithmic scale for the variable concerned is
> > usually the
> > best way forward.
>
> Timothy Dang
>
> > > I'm making a lot of (line) plots in Stata, and mostly it's working
> > > great, but I've hit a snag. For a few of my data sets,
> > there are some
> > > data points which are extraordinarily high. With the automatically
> > > scaled axis ranges, these points are visible, but all the detail of
> > > the rest of the data is shrunk to invisibility.
> > >
> > > So, I want to:
> > > (a) enforce a maximum for the axis, hopefully showing the
> > lines going
> > > up towards some point not shown on the plot, and
> > > (b) add some text describing what happens at those points (I can do
> > > this outside Stata if needed).
> > >
> > > Hopefully this is straightforward and I've just missed something.
> > > Thanks for any pointers.
>
> *
> * For searches and help try:
> * http://www.stata.com/support/faqs/res/findit.html
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
--
------------------------------
Timothy O'Neill Dang / Cretog8
520-884-7261
One monkey don't stop no show.
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
