Re: st: When to use Log (1+x) Transformation?

["Song" <raravise@gmail.com>]

Maarten,

I understand your point. I plan to estimate the following model by 3SLS 
(reg3).

ln(Revenue in each country) = a0 + a1*time window + controls.
ln(time window) = b0 + b1*(expected) Revenue in each country + controls.

Time window is difference in launching time (in days) of a product between 
the US and international launch. Both revenue and time window are skewed, so 
I wanted to use log transformation. The problem is that time window includes 
a lot of zeros, so I am not sure what is the best method. Can you suggest a 
good method? Do you still think glm and spline will work in this situation?

Thank you,
Reo.

----- Original Message ----- 
From: "Maarten buis" <maartenbuis@yahoo.co.uk>
To: <statalist@hsphsun2.harvard.edu>
Sent: Sunday, April 06, 2008 1:01 PM
Subject: Re: st: When to use Log (1+x) Transformation?



> --- Song wrote:
> > I need to use log transfomation for both my dependent variable
> > and independent variables.
> I always get rebellious as soon as someone says the he or
> she
> "must" or "needs to" use some technique or do some
> transformation. Statistics
> does not force you do anything. The
> only thing you must do is make sense.
> Statistics books are full
> of rules of thumb and tips that will often help
> making sensible
> decision. It these "rules" that people often mean
> when they say
> that they "must" do something. I have two problems with
> that:
>
>
> 1) You are the only one who is responsible for your decisions.
>
> You are hiding
> from that responsibility by saying that you "must"
>
> do something (at least as long as you do not tell why this is the
>
> case).
>
> 2) Such rules help in general but often do not apply to your
>
> specific research
> project. The only one who can see that is you.
>
> This is a general rant, and I hope you do not take this personally.
>
> It is just
> that this issue is bothering me for some time, and you
>
> just made this remark at
> a time that I had time to write it up.
>
> Also, I am a non-native speaker, so it
> may very well be that I read
>
> too much in the word need in this context
>
> -- Maarten
> -----------------------------------------
> Maarten L. Buis
> Department of Social Research Methodology
> Vrije Universiteit Amsterdam
> Boelelaan 1081
> 1081 HV Amsterdam
> The Netherlands
>
>
> visiting address:
> Buitenveldertselaan 3 (Metropolitan), room Z434
>
> +31 20 5986715
>
> http://home.fsw.vu.nl/m.buis/
> -----------------------------------------
>
>
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