st: Scatter and line graphs with by option

[Beatrice Crozza <beatrice.crozza@gmail.com>]

Dear All,

I am trying to graph the volume of my security for each day,
considering the time, because I want to consider possbile time of the
day effects.

I typed:

scatter volume time, by (date)

but I receive the error message: option by() not allowed.

However, I found this example which uses the option by:

//Changing the order of twoway graphs where the by() option is used:

http://www.survey-design.com.au/Stata%20Graphs.html

Could you please help me?

Thank you very much,
Bea
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