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Re: AW: st: prgen option quadratic term

From   Nick Cox <>
Subject   Re: AW: st: prgen option quadratic term
Date   Wed, 7 Nov 2012 11:36:09 +0000

So, you can see what the fit implies statistically. What is your
question then? If you want help with (socio-)economic interpretation,
even people in your field would need to be told what your outcome or
response variable is. Here it's just -y-.


On Wed, Nov 7, 2012 at 11:29 AM, Meulemann  Max <> wrote:

> I had hoped that was taken care of by the margins command
> ologit y capitagdp c.capitagdp#c.capitagdp i.socioecovars
> margins, at(c_capitagdp=(0.5(0.5)9))  atmeans predict(outcome(4))
> marginsplot
> which looked the same as
> ologit y c_logcapitagdp c_logcapitagdpsquared $socioecovars
> oprobpr c_logcapitagdp, levels(c_logcapitagdpsquared=c_logcapitagdp^2) cat(4) newobs(100)
> In the linear model that graph is downward slooping and in the quadratic model it is downward slooping and then turning up
> ________________________________________
> Von: []&quot; im Auftrag von &quot;Nick Cox []

> When you are fitting a linear term and a quadratic term, the two act
> together. It's their combined effect that you need to interpret. This
> is usually easier with a graph. For example, one negative coefficient
> and one positive coefficient mean a turning point somewhere, but not
> necessarily within the range of the data.
> Nick
> On Wed, Nov 7, 2012 at 10:35 AM, Meulemann  Max <> wrote:
>> thx, the margins and marginsplot function helped a lot.
>> Anyways anybody got a idea how I am to interpret my data here: I find a negativ linear term for capitagdp, but if i include a quadratic gdp term, that one turns out to be positiv and significant with a lrtest.
>> Plotting with marginsplot tells me then that for the linear model the probability to agree with a certain issue decreases whereas it increases with capitagdp for the quadratic model, keeping fixed my other covariates

>> Von: []&quot; im Auftrag von &quot;Maarten Buis []

>> Also see: <>
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