Graphics Reference
In-Depth Information
twoway (
scatter
propval100 popden) (
lfit
propval100 popden)
Stata allows us to overlay
twoway
graphs. In this case, we make a classic
plot showing a scatterplot overlaid with
a fit line using the
scatter
and
lfit
commands. For more details about
overlaying graphs, see
Twoway : Overlaying
(87).
Uses allstates.dta & scheme vg s2c
0
2000
4000
6000
8000
10000
Pop/10 sq. miles
% homes cost $100K+
Fitted values
twoway (
scatter
propval100 popden) (
lfit
propval100 popden)
(
qfit
propval100 popden)
The ability to combine
twoway
plots is
not limited to just overlaying two plots;
we can overlay multiple plots. Here, we
overlay a scatterplot with a linear fit
line (
lfit
) and a quadratic fit line
(
qfit
).
Uses allstates.dta & scheme vg s2c
0
2000
4000
6000
8000
10000
Pop/10 sq. miles
% homes cost $100K+
Fitted values
Fitted values
twoway (scatter propval100 popden) (
mspline
propval100 popden)
(
fpfit
propval100 popden) (
mband
propval100 popden)
(
lowess
propval100 popden)
Stata has other kinds of fit methods in
addition to linear and quadratic fits.
This example includes a median spline
(
mspline
), fractional polynomial fit
(
fpfit
), median band (
mband
), and
lowess (
lowess
). For more details, see
Twoway : Fit
(49).
Uses allstates.dta & scheme vg s2c
0
2000
4000
6000
8000
10000
Pop/10 sq. miles
% homes cost $100K+
Median spline
predicted propval100
Median bands
lowess propval100 popden
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