From: David Winsemius <dwinsemius_at_comcast.net>

Date: Fri, 08 Apr 2011 08:15:15 -0400

R-help_at_r-project.org mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Fri 08 Apr 2011 - 12:21:33 GMT

Date: Fri, 08 Apr 2011 08:15:15 -0400

On Apr 8, 2011, at 4:24 AM, Tomii wrote:

> Thank you for your response, but these changes doesn't seem to change

*> anything, outcomes of effect command is still the same - error.
**>
**> Tomas
**>
**> On Fri, Apr 1, 2011 at 5:03 AM, John Fox <jfox_at_mcmaster.ca> wrote:
**>
**>> Dear Tomas,
**>>
**>> Write the model as
**>>
**>> mreg01 = lm(enep1 ~ enpres * proximity1), data=a90)
*

A syntactic comment only. Perhaps:

mreg01 = lm(enep1 ~ enpres * proximity1, data=a90)

--

David

*>>
*

>> That is, it's not necessary to index a90 as a list since it's given

*>> as the
**>> data argument to lm, and doing so confuses the effect() function.
**>> Also,
**>> enpres*proximity1 will include both the enpres:proximity1
**>> interaction and
**>> enpres + proximity1, which are marginal to the interaction.
**>>
**>> Next, you must quote the name of the term for which you want to
**>> compute
**>> effects, thus "enpres:proximity1" in the call to effect().
**>>
**>> Finally, effect() doesn't compute what are usually termed marginal
**>> effects.
**>> If you want more information about what it does, see the references
**>> given in
**>> ?effect.
**>>
**>> I hope this helps,
**>> John
**>>
**>> ------------------------------------------------
**>> John Fox
**>> Sen. William McMaster Prof. of Social Statistics
**>> Department of Sociology
**>> McMaster University
**>> Hamilton, Ontario, Canada
**>> http://socserv.mcmaster.ca/jfox/
**>>
**>> On Thu, 31 Mar 2011 22:09:32 +0200
**>> Tomii <diogenas_at_gmail.com> wrote:
**>>> Hello,
**>>>
**>>> I try to plot the marginal effect by using package
**>>> "effects" (example of
**>> the
**>>> graph i want to get is in the attached picture).
**>>> All variables are continuous.
**>>>
**>>> Here is regression function, results and error effect function
**>>> gives:
**>>>
**>>>> mreg01 = lm(a90$enep1 ~ a90$enpres + a90$proximity1 + (a90$enpres *
**>> a90$proximity1), data=a90)> summary(mreg01)
**>>> Call:
**>>> lm(formula = a90$enep1 ~ a90$enpres + a90$proximity1 + (a90$enpres *
**>>> a90$proximity1), data = a90)
**>>>
**>>> Residuals:
**>>> Min 1Q Median 3Q Max
**>>> -2.3173 -1.3349 -0.5713 0.8938 8.1084
**>>>
**>>> Coefficients:
**>>> Estimate Std. Error t value Pr(>|t|)
**>>> (Intercept) 4.2273 0.3090 13.683 < 2e-16 ***
**>>> a90$enpres 0.4225 0.2319 1.822 0.072250 .
**>>> a90$proximity1 -3.8797 1.0984 -3.532 0.000696 ***
**>>> a90$enpres:a90$proximity1 0.8953 0.4101 2.183 0.032025 *
**>>> ---
**>>> Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
**>>>
**>>> Residual standard error: 2.029 on 78 degrees of freedom
**>>> Multiple R-squared: 0.2128, Adjusted R-squared: 0.1826
**>>> F-statistic: 7.031 on 3 and 78 DF, p-value: 0.0003029
**>>>> plot(effect(a90$enpres:a90$proximity1, mreg01))Warning messages:
**>>>> 1: In
**>> a90$enpres:a90$proximity1 :
**>>> numerical expression has 82 elements: only the first used2: In
**>>> a90$enpres:a90$proximity1 :
**>>> numerical expression has 82 elements: only the first used3: In
**>>> analyze.model(term, mod, xlevels, default.levels) :
**>>> 0 does not appear in the modelError in
**>>> plot(effect(a90$enpres:a90$proximity1, mreg01)) :
**>>> error in evaluating the argument 'x' in selecting a method for
**>>> function
**>> 'plot'
**>>>
**>>>>
**>>>
**>>> Thanks in advance.
**>>> Tomas
**>>
**>>
**>>
**>>
**>
**> [[alternative HTML version deleted]]
**>
**> ______________________________________________
**> R-help_at_r-project.org mailing list
**> https://stat.ethz.ch/mailman/listinfo/r-help
**> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
**> and provide commented, minimal, self-contained, reproducible code.
*

David Winsemius, MD

West Hartford, CT

R-help_at_r-project.org mailing list

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