Introduction to Stata 8 - (GRIPS

twoway function
-3.00 -1.96 -1.00 0.00 1.00 1.96 3.00
Standard deviations from mean
// c:\dokumenter\...\gph.normal.do
set scheme lean2
twoway ///
(function y=normden(x) , range(-3.5 3.5) ///
droplines(-1.96 -1 0 1 1.96)) ///
, ///
plotregion(margin(zero)) ///
yscale(off) ylabel(, nogrid) ///
xlabel(-3 -1.96 -1 0 1 1.96 3 , format(%4.2f)) ///
xtitle("Standard deviations from mean") ///
xsize(3) ysize(2.3) scale(1.4)
twoway function gives you the opportunity to visualize any mathematical function. The
result has no relation to the actual data in memory. The range() option is necessary; it
defines the x-axis range.
Other examples:
An identity line, to be overlaid in a scatterplot comparing two measurements:
twoway ///
(scatter sbp2 sbp1) ///
(function y=x , range(sbp1))
A parable:
twoway (function y=x^2 , range(-2 2))
50