Perhaps I have too much time on my hands as I try to not think about my
psychometrics course tomorrow:
library(psych) #needed for the dia.ellipse function
#create a new function
"bullseye" <- function(x,y,n) {
for(i in 1:n) {dia.ellipse(x,y,e.size=i)}}
plot(NA,xlim=c(0,10),ylim=c(0,10),axes=FALSE,xlab="",ylab="") #make a frame
for the pictures
#Reliable and vallid
x=3
y=3
n=5
lim<-c(-.2,.2)
bullseye(x,y,4)
points(x+runif(n,lim[1],lim[2]),y+runif(n,lim[1],lim[2]),pch=16)
#reliable and invalid
x=7
y=3
bullseye(x,y,4)
points(x+1+runif(n,lim[1],lim[2]),y+1+runif(n,lim[1],lim[2]),pch=16)
#unreliable, but valid
x=5
y=8
n=5
lim<-c(-1,1)
bullseye(x,y,4)
points(x+runif(n,lim[1],lim[2]),y+runif(n,lim[1],lim[2]),pch=16)
Bill
On Mar 25, 2012, at 8:29 AM, Jeff Laux wrote:
> It doesn't seem silly to me; this is a standard figure/metaphor for teaching
> reliability & validity. You could make such a figure in R, but I would
> probably just use a drawing program (e.g., Serif, which can be downloaded for
> free). Alternatively, you could just search the internet for one, as I've
> seen several versions of this before. -Jeff
>
>
> On 3/25/2012 8:59 AM, AbouEl-Makarim Aboueissa wrote:
>> Dear R users:
>>
>> It may be a silly question. I am trying to create a target diagram of 4
>> circles inside each other and adding some dots to describe different
>> situations of validity and reliability. I need three of them.
>>
>> one with all dots around the target.
>> one with all dots in about one place, but far from the target.
>> one with randomly scattered dots.
>>
>> I tried my best, but could not succeed. Can someone help me with creating
>> such graph.
>>
>> Thank you very much
>> abou
>>
>>
>>
>> ==========================
>> AbouEl-Makarim Aboueissa, Ph.D.
>> Associate Professor of Statistics
>> Graduate Program Coordinator
>> Department of Mathematics& Statistics
>> University of Southern Maine
>> 96 Falmouth Street
>> P.O. Box 9300
>> Portland, ME 04104-9300
>> USA
>>
>>
>> Tel: (207) 228-8389
>> Fax: (207) 780-5607
>> Email: [email protected]
>> [email protected]
>>
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>>
>>
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William Revelle http://personality-project.org/revelle.html
Professor http://personality-project.org
Department of Psychology http://www.wcas.northwestern.edu/psych/
Northwestern University http://www.northwestern.edu/
Use R for psychology http://personality-project.org/r
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