R help - Nov 2015 - R: RE: How to plot results from lme in presence of a significant interaction

Dear prof. Fox,
thank you very much

Best regards

Angelo
>----Messaggio originale----
>Da: jfox at mcmaster.ca
>Data: 23-nov-2015 12.50
>A: "angelo.arcadi at virgilio.it"<angelo.arcadi at
virgilio.it>
>Cc: "r-help at r-project.org"<r-help at r-project.org>
>Ogg: RE: [R] How to plot results from lme in presence of a significant 
interaction
>
>Dear Angelo,
>
>You might try the Effect() function in the effects package: plot(Effect(c
("Weight", "Height"), lme_Centroid))
.
>
>I hope this helps,
> John
>
>-----------------------------
>John Fox, Professor
>McMaster University
>Hamilton, Ontario
>Canada L8S 4M4
>Web: socserv.mcmaster.ca/jfox
>
>
>
>> -----Original Message-----
>> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of
>> angelo.arcadi at virgilio.it
>> Sent: November 22, 2015 5:44 PM
>> To: r-help at r-project.org
>> Subject: [R] How to plot results from lme in presence of a significant 
interaction
>> 
>> Dear list members,
>> I wonder which is the best way to plot in r the results from the lme 
function, in
>> presence of a significant interaction.
>>  My model has two interacting fixed effects and a random effect. The 
analysis is
>> from an experiment where 19 participants had to adjust the Centroid
>> parameter of some sounds stimuli, and I want to assess whether  there
is a
>> relationship between their choices and their height and weight. There
were
12
>> stimuli repeated twice for a total of 24 trials.
>> Here is the output of my analysis:
>> 
>>     > library(nlme)
>>     > lme_Centroid <- lme(Centroid ~ Weight*Height, data = scrd,
random =
~1 |
>> Subject)
>>     >
>>     > summary(lme_Centroid)
>>     Linear mixed-effects model fit by REML
>>      Data: scrd
>>            AIC      BIC    logLik
>>       25809.38 25840.69 -12898.69
>> 
>>     Random effects:
>>      Formula: ~1 | Subject
>>             (Intercept) Residual
>>     StdDev:    398.9658  3027.67
>> 
>>     Fixed effects: Centroid ~ Weight * Height
>>                        Value Std.Error   DF   t-value p-value
>>     (Intercept)   -20232.203  9101.096 1349 -2.223051  0.0264
>>     Weight           478.854   152.184   15  3.146536  0.0067
>>     Height           140.440    52.194   15  2.690751  0.0168
>>     Weight:Height     -2.725     0.838   15 -3.253770  0.0053
>>      Correlation:
>>                   (Intr) Weight Height
>>     Weight        -0.927
>>     Height        -0.994  0.886
>>     Weight:Height  0.951 -0.996 -0.919
>> 
>>     Standardized Within-Group Residuals:
>>            Min         Q1        Med         Q3        Max
>>     -1.5059828 -0.8664208 -0.2111113  0.7098706  2.3620633
>> 
>>     Number of Observations: 1368
>>     Number of Groups: 19
>> 
>> 
>> 
>> I
>>  do not know how to represent in R these results. I tried
xyplot(Centroid ~
>> Weight * Height, type = c("p","r"), data = scrd)
but I  guess it is wrong.
>> 
>> Thank you in advance
>> 
>> Best regards
>> 
>> Angelo
>> 	[[alternative HTML version deleted]]
>> 
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>