Multiple lines using lgraph

[Falak Amjad]

Hi,
I need help in drawing multiple lines using lgraph. I am a stata beginner and need help for my thesis.
I have three y variables (ENV, SOC, CGV) all with the same units and year as x-variable.
I use the following command to generate a line graph plotting mean of each variable in a given year:
lgraph ENV YEAR
lgraph SOC YEAR
lgraph CGV YEAR

Is there a way i show all the lines together in one graph?

Thanks.

[Marcos Almeida]

Welcome to the Stata Forum / Stalist.

Please read the FAQ, mainly on how to share data and command.

I gather - lgraph - is a user-written program, whose author is Timothy Mak.

Share data - or at least a small parcel - increases the odds of a helpful reply.

[George Ford]

I frequently use Timothy Lak's -lgraph- option with panel data. It uses the -collapse- option (with a hidden -preserve-) and draws a -connected- graph with the -by- option. The help file describes but provides no examples on how to add an additional plot to the graph. While I eventually figured it out, it is just as easy to use the -collapse- and -connected- options directly. Here's the way you would implement it for your problem.

preserve
collapse (mean) ENV SOC CGV , by(t)
twoway (connected ENV YEAR, legend(all)) (connected SOC YEAR, legend(all)) (connected CGV YEAR, legend(all))
restore

[Nick Cox]

I guess that you meant

preserve
collapse (mean) ENV SOC CGV , by(YEAR)
twoway (connected ENV YEAR, legend(all)) (connected SOC YEAR, legend(all)) (connected CGV YEAR, legend(all))
restore

as the collapse command (not an option) won't produce a variable YEAR if it didn't exist. (lgraph (from SSC) is also a command, while connected is a subcommand.)

More interestingly, your syntax can be simplified further. Setting aside a preserve and restore, this reproducible example shows how:

webuse grunfeld, clear
collapse invest mvalue kstock, by(year)
twoway connected invest mvalue kstock year

[George Ford]

Thanks Nick--a much cleaner -twoway- statement. That "t" instead of "YEAR" was a typo.