One of the nicer thngs about Stata in general is that there are often
multiple ways to "skin the cat' so to speak, i.e. there are often
alternative ways to do something. Graphing data may be a case in point.
While using a collapse may work in some instances, there are certainly
alternatives, and the alternatives can allow easier implemetnation of error
bars. (maybe even alternative "collapses", I haven't thought about or
looked at the possibilities). XTGRAPH is a case in point. I don;t think
this capability is all that unusual or difficult to implement, though it
might in some instances require a second approach to some graph types. It
is absolutely, however, doable.
1. Stata should support error bars on graphs
I agree with this. What's more, I don't think
it's at all controversial. The only issue that
is how it is supported. It so happens that
Stata's been a bit laggard on producing
wrapper commands for plots showing error bars.
I doubt there's any policy there.
However, having implemented various high-
level commands in one way does inhibit twisting
them in a different direction. -graph bar-
for example is basically built around a -collapse-
of the data. Building something else major on top of
that, such as machinery for adding confidence
intervals generally, would be, I guess, rather tricky.
"Wrong" from the standpoint of authors instructions in the specific case I
was reflecting on. I have panel data repeated in time, for which XTGRAPH
works nicely, except for the error bars, which overlay the empty symbols.
In essence, using XTGRAPH and the half option, the error bar "marker" at
the line end where the datapoint is plotted overlies the datapoint symbol,
which, if it is an open symbol, means the point ends up to be a marker
within a marker. The authors instructions for the journal specify that
should not occur. Could I get away with it? Maybe. Do other graphics
routinely published in that journal adhere to the instructions? Yes. Does
the instruction make reasonable sense in terms of clarity of the graphics?
Yes. I don't think it is an unreasonable recommendation, and using other
software I can adhere to it. But, I like keeping my work in Stata for
several reasons, and I think I should be able to do a better job with this
in Stata. As it was, I went to Stata8 (XTGRAPH is a version 7 command),
and reconstructed this so I could have better control over the markers. It
works, but at a considerable investment of time to get error bars into the
2. Specific problems experienced by Buzz
Buzz: could you revisit this with concrete
examples of what you typed and what is
wrong or unsatisfactory about it? I may
not be the only one to be unclear about precisely
what syntax you are using. It is difficult, possibly
even for the graphics experts at Stata, to know
what you're missing which is there in Stata and
what you're missing which is not.