Introduction to Stata 8

In bar graphs the x-axis is categorical, the y-axis continuous. In the example variables m and
f defined the heights of the bars, but actually graph bar used the default mean function,
as if the command were (with one observation per bar the result is the same):
graph bar (mean) m f , over(age)
With the auto.dta data you could generate bars for the number of domestic and foreign
cars by:
graph bar (count) mpg , over(foreign)
Actually what is counted is the number of non-missing values of mpg.
Bar graphs are documented in [G] graph bar and [G] graph twoway bar.
twoway
scatter
Mileage (mpg)
40
30
20
10
2,000 3,000 4,000 5,000
Weight (lbs.)
/ / c:\dokumenter\...\gph.mpg_weight.do
clear
sysuse
auto
set
scheme lean2
Domestic
Foreign
twoway ///
(scatter mpg weight if foreign==0, msymbol(Oh)) ///
(scatter mpg weight if foreign==1, msymbol(O)) ///
, ///
legend(label(1 "Domestic") label(2 "Foreign")) ///
xsize(4) ysize(2.3) scale(1.4)
Twoway graphs have continuous x- and y-axes; scatter is the "mother" of twoway graphs.
A graph with one plot has no legend; this one with two plots has. The default legend texts
often need to be replaced by short, distinct texts, like here. Since the xtitle() and
ytitle() options were not specified, Stata used the variable labels as axis titles.
msymbol may be abbreviated to ms; I chose to avoid abbreviations for readability; it is
much more important that commands are easy to read than easy to write. In this case the
msymbol() options were not necessary since (Oh) and (O) are the default first symbols
under the lean schemes.
The graph displays the same data as the initial Figure 1, this time using the scheme lean2:
The plot area has horizontal grid-lines, but no frame.
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