I am sending this to the stata list because I use the Unix version in a
shared environment, and owing to many complexities I have not used the
graphics of stata. But, I am thinking of buying a laptop and graphics
would be a consideration for statistical software purchases. The laptop
may run Linux, I'm still thinkin', but the big question concerns effort.
Before I invest great effort in learning how to use the graphics in stata,
maybe some set of people can confirm the wisdom of making the investment,
or warn me to look elsewhere for a solution to some graphic aims I have. I
also hope that this note will be of use to others.
My graphics wishlist:
1)I want to be able to write down a function (e.g., Y=b0 + b1*X1;
Pr(y=1)=(e(b0+b1*X1))/(1+e(b0+b1*X1)) ) and have it graphed.
2)I want to be able to write down multiple functions, and have them appear
on the same graph (I will need 6 different functions in my current
application).
3)I want to be able to have a legend saying what lines go with what
function.
4)I want to be able to provide a series that tells where the tick marks
should be. Something like (xtick=0,.1, .2, .3, . . . , 1.0). This would
be of most use, of course, if the graph started at .27, but I still wanted
tick marks on the .3, .4, and such, not at wierd values.
5)I want the graph to have a range for the axes, but I also want to be
able to specify *different* limits for each function. In pictures, using
two lines as illustration, I want to be able to do something like the
following:
| /
| ./
| /.
| .
| .
|_________
The dashed line going up (from left to right) does not have the same range
in X as the dotted line (the dotted line is going down from left to
right). This is not a feature of the function but is, instead, a feature
of the data used to estimate the model that produced the function; the
range of X is smaller for one group than the other, so I don't want the
line for any group to exceed the range of the data from which I estimated
the function.
6)The above is great, but it would also be nice to draw the line over the
full range of X, and mark certain points on each line. The figure below
illustrates what I mean
|. /
| - -
| ./
| /.
| / _
|- .
/______
This would let me have my cake (the horizontal lines showing the limits of
defensible if slightly improper inference) and eat it too (the full line,
showing the logical implications if all groups had the same range--useful
perhaps only for illustration, not inference.
The above could be secured by shading, symbols, or whatever.
7)Multiple lines for titles.
8)Easy ability to switch between landscape and portrait page orientation.
9)Now, this is really(!) tough, but would be ***great***! This is more
for presentation in a class or among a group of non-statisticians. I'd
love to estimate a model on some data, then have it draw the line showing
the predicted values on some Y given some (varying) X, at means on the
other Xs (or at prespecified values for categorical data), and THEN let me
re-estimate the model with another X added (X_new) (ideally, as suggested
by the students in the class), and THEN let me draw the old X-Y relation
and another line (dashed, let's say) with the new X-Y relation (once the
X_new) is controlled. I can think of nothing more able to quickly convey
to students the value of statistical modelling. I admit this is the outer
limit of my wish list at this time.
Can Stata do these things in the graphics module?
Thanks for any assistance you can provide. And, I apologize if this wish
list causes anyone any pain or frustration.
Thanks.
Sam
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