R: st: About difference in differences estimation

["Carlo Lazzaro" <carlo.lazzaro@tiscalinet.it>]

Lynn wrote:
"I have no idea about user-written command and Stata command. Is that mean
user-written command are not allowed to be used by researchers? ".

Dear Lynn,
the rationale of the FAQ about stating where did you get the user-written
software you quote in your post (better if with author(s)' name(s), too), is
simpy the one already provided by Maarten in one of his previous replies:
"there are often different versions of user written software floating around
in cyberspace. If you do not tell us where you got it from, than there is a
real chance that we are talking about different commands, and that is
helping nobody". This FAQ doesn't imply that user-written softwares are not
allowed to be used by researchers.

Kindest Regards,
Carlo


-----Messaggio originale-----
Da: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] Per conto di Lynn Lee
Inviato: lunedì 17 settembre 2012 12:38
A: statalist@hsphsun2.harvard.edu
Oggetto: RE: st: About difference in differences estimation

The Stata11 was installed in my computer by my friend, a university staff
who is in charge of  all campus-use softwares. And this installation was not
free. Per your question, I really do not know why I can get "diff" command
by typing help. It may be installed in my computer at the same time when my
friend installed the software. I searched website about how to run DID in
Stata, and I learned that command -diff- can help. That is all the sources I
got about DID. I am not sure your question about where I got this -diff-. I
am not expert in computer science, and when I type "help diff", Stata gives
me the instruction of DID. So, this command should be installed at the same
time my friend installed Stata11 for me. 

I have no idea about user-written command and Stata command. Is that mean
user-written command are not allowed to be used by researchers? I was not
informed about this when I purchased usage of this software. So sorry about
this. 

Best Regards,
Lynn Lee

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Maarten Buis
Sent: Monday, September 17, 2012 4:12 PM
To: statalist@hsphsun2.harvard.edu
Subject: Re: st: About difference in differences estimation

On Mon, Sep 17, 2012 at 9:21 AM, Lynn Lee wrote:
> I got this "diff" command in Stata11 by typing "help diff". The syntax 
> is
"
> diff outcome_var [if] [in] [weight] ,[ options]".

That cannot be true: -help- only knows only about things that are on your
computer. User written software is not provided to you by StataCorp (but by
users, hence the name), so when you install Stata, you are not installing
any user written software. So -help- cannot install user written software.
You must have done so separately.

-- Maarten

---------------------------------
Maarten L. Buis
WZB
Reichpietschufer 50
10785 Berlin
Germany

http://www.maartenbuis.nl
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