Thank you very much Martin.
I tried the example and it worked perfectly. When I tried with my
variables, the one that replaces mpg has one value that is not an
integer but is 42.6, therefore I got an error message:
levels varmain
varmain contains non-integer values
r(459);
I guess I should change the command -levels- with another one that
could list the values of varmain.
Also, I tried to recode varmain (42.6=43) but then I don't get
anything inside the new variable marg that keeps the marginal effects.
I am sure something is not right there because your example works
perfectly. I am going through each line to check.
Nirina
On Thu, Sep 17, 2009 at 6:19 PM, Martin Weiss <[email protected]> wrote:
>
> <>
>
> Try this and check it very carefully. I could not find such a picture in
> Long and Freese (2006), http://www.stata-press.com/books/regmodcdvs.html, -
> which I regard as a bad sign.
>
> Also note I am using the old -mfx- here, as I have not fully gotten my head
> round the -margins- command. Hence the -version- statement...
>
>
> *************
> vers 10.1
>
> qui{
> sysuse auto, clear
> prob for price mpg rep78 /*
> */ headroom trunk weight
>
> ins mpg
> loc uniq= r(N_unique)
>
> su mpg, mean
> prgen mpg, from(`r(min)') /*
> */ to(`r(max)') /*
> */ gen(prob) n(`uniq')
>
>
> levels mpg
>
> loc i 1
> gen marg=0
>
> foreach level in `r(levels)'{
> mfx, var(mpg) at(mpg=`level')
> mat A = e(Xmfx_dydx)
> replace marg=A[1,2] in `i'
> loc ++i
> }
>
> }
>
> tw (connected probp1 probx), /*
> */ xti("Mpg") ytit("Probability") /*
> */ name(prob, replace) nodraw
>
> tw (connected marg probx), /*
> */ xti("Mpg") ytit("Marginal Effect") /*
> */ name(marginal, replace) nodraw
>
>
> gr combine prob marginal
> *************
>
>
>
> HTH
> Martin
>
>
> -----Ursprüngliche Nachricht-----
> Von: [email protected]
> [mailto:[email protected]] Im Auftrag von Nirina F
> Gesendet: Donnerstag, 17. September 2009 18:46
> An: [email protected]
> Betreff: Re: st: AW: why is this graph all over the place?
>
> Dear Martin,
>
> Thank you very much for the clarification.
> How about graphing the marginal effects next to that graph?
> nrina
>
> On Thu, Sep 17, 2009 at 12:04 PM, Martin Weiss <[email protected]> wrote:
>>
>> <>
>>
>> The -prgen- command holds all other covariates at their mean by default,
> so
>> my code has already taken care of your concern. To change the -title-s:
>>
>> *************
>> sysuse auto, clear
>> prob for price mpg rep78 /*
>> */ headroom trunk weight
>>
>> ins mpg
>> loc uniq= r(N_unique)
>>
>> su mpg, mean
>> prgen mpg, from(`r(min)') /*
>> */ to(`r(max)') /*
>> */ gen(prob) n(`uniq')
>>
>> tw (connected probp1 probx), /*
>> */ xti("Mpg") ytit("Probability")
>> *************
>>
>>
>>
>> HTH
>> Martin
>>
>>
>> -----Ursprüngliche Nachricht-----
>> Von: [email protected]
>> [mailto:[email protected]] Im Auftrag von Nirina F
>> Gesendet: Donnerstag, 17. September 2009 17:55
>> An: [email protected]
>> Betreff: Re: st: AW: why is this graph all over the place?
>>
>> Thank you very much Martin for your help. It worked so well.
>>
>> I have a few questions:
>>
>> is it possible also to graph the marginal effects of just the mpg at
>> each value of mpg. I know if you calculate
>> . mfx
>> after
>> . prob for price mpg rep78 headroom trunk weight
>>
>> then you get the marg. effects at the mean value but I would like the
>> marginal effects at each value of mpg but keeping the other variables
>> at their mean. I am aware of the -at- option but it's just difficult
>> to graph it.
>>
>> Also, How would I change the name of the xaxis and yaxis of the previous
>> graph?
>>
>> Thank you very much,
>>
>> Nrina
>>
>>
>> On Thu, Sep 17, 2009 at 8:00 AM, Martin Weiss <[email protected]>
> wrote:
>>>
>>> <>
>>>
>>> For these purposes, Scott Long`s -findit spost- comes in handy. Of
> course,
>>> Long and Freese (2006), http://www.stata-press.com/books/regmodcdvs.html,
>> is
>>> the canonical reference for what you are trying to achieve. Try this:
>>>
>>>
>>> *************
>>> sysuse auto, clear
>>> prob for price mpg rep78 /*
>>> */ headroom trunk weight
>>>
>>> ins mpg
>>> loc uniq= r(N_unique)
>>>
>>> su mpg, mean
>>> prgen mpg, from(`r(min)') /*
>>> */ to(`r(max)') /*
>>> */ gen(prob) n(`uniq')
>>>
>>> tw (connected probp1 probx)
>>> *************
>>>
>>>
>>>
>>> HTH
>>> Martin
>>>
>>>
>>> -----Ursprüngliche Nachricht-----
>>> Von: [email protected]
>>> [mailto:[email protected]] Im Auftrag von Nirina F
>>> Gesendet: Donnerstag, 17. September 2009 13:41
>>> An: [email protected]
>>> Betreff: st: why is this graph all over the place?
>>>
>>> Dear all,
>>>
>>> I would like to graph the predicted probabilities of having foreign
>>> against mpg in order to highlight the slope(basically the marginal
>>> effects) at each value of mpg.
>>> I run the following but it is all over the place because I think it is
>>> giving me the predicted probabilities from different variables.
>>> Could you help me in this please. also if you could help me graph the
>>> marginal effects of mpg from this probit equation against each value
>>> of mpg.
>>>
>>> probit foreign price mpg rep78 headroom trunk weight
>>> predict pmpg, p
>>> sort mpg
>>> twoway line pmpg mpg
>>>
>>> Thank you veyr much,
>>> N
>>> *
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>>
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