# RE: st: mfx - conditional and unconditional elasticities

 From Even Bergseng <[email protected]> To "[email protected]" <[email protected]> Subject RE: st: mfx - conditional and unconditional elasticities Date Thu, 20 Dec 2007 19:16:19 +0100

```Thanks, Austin.

That's valuable input. I'll keep away from selecting at Y's then.

But my interpretation of the -mfx- options is correct?

regards,
Even

>-----Original Message-----
>From: [email protected] [mailto:owner-
>[email protected]] On Behalf Of Austin Nichols
>Sent: Thursday, December 20, 2007 4:41 PM
>To: [email protected]
>Subject: Re: st: mfx - conditional and unconditional elasticities
>
>Even Bergseng <[email protected]>:
>I think not.  Predicting at some X=x is a way of
>characterizing/interpreting the model's estimated coefficients;
>selecting on the explanatory variables X in creating a subsample to
>predict over (or to compute means of X at which to predict) is
>unproblematic, and relatively easy to interpret for a simple selection
>rule, e.g. X=(female, college).  Selecting on y seems like a bad idea
>for all kinds of reasons.
>
>On Dec 20, 2007 10:31 AM, Even Bergseng <[email protected]> wrote:
>> I want to use -mfx- to compute elasiticities after -tobit/xttobit-. My
>interpretation is that the commands
>>
>> . mfx compute, eyex predict(ystar(0,.))
>> . mfx compute, eyex predict(e(0,.))
>>
>> should produce respectively unconditional (all observations) and
>conditional (non-limit observations) elasticities. Am I correct?
>>
>> If so: Both elasticities are interpreted at the mean of all
>observations. Would it be logical to use mean values for the non-limit
>sample to produce the conditional elasticities? (i.e. add the option
>at(avg) to mfx where avg is means for the non-limit sample).
>>
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```