Drawing a line (function) overlaid on a Scatter Plot

[Vincent La]

Hi All,

Sorry if this is a really basic question, but I've searched and looked at the help files, and I can't seem to figure this out. I would like to overlay a line (defined by a function) on a scatter plot in Stata 13.1. Here's a reproducible sample:

clear
set more off

input c y i
46 60 14
31 45 14
61 75 14
58 80 22
43 65 22
73 95 22
70 100 30
55 85 30
85 115 30
end

graph twoway  (scatter c y)

Now, for example, if I were trying to just fit the regression line I would use

graph twoway (scatter c y) (lfit c y)

But if I try to do something with function to overlay a line defined by an equation:

graph twoway (scatter c y) (function y = 0.6*x+10)

It doesn't actually give me the line defined by the function.

Thank you in advance for your help!

Vincent

[Jeff Pitblado (StataCorp)]

For twoway function, the default range for the x axis is range(0 1).

Try adding option range(y) to the function plot.
The y in range(y) refers to a variable in the dataset, which turns
out to be the x variable in your scatter plot.

graph twoway (scatter c y) (function y = 0.6*x+10, range(y))