[R] linear correlation?

[Andrew Perrin]

On Thu, 7 Mar 2002, Joerg Maeder wrote:

> Hello 
> 
> dechao wang wrote:
> > 
> > Hi, I have checked statistic textbooks about
> > correlations, but I am still not sure the correlation
> > analysis with different units, for example,
> > 
> > x1<-c(1,  2,  3,   100, 200, 300)
> > x2<-c(1.1,2.8,3.3, 108, 209, 303)
> > the unit of the first 3 numbers is cm
> > the unit of the last 3 numbers is kg
> > 
> > cor(x1,x2)=0.999655
> > 
> > Can I explain the correlation coefficient as normal in
> > which all numbers have the same unit?
> 
> No, that will give different results. The unit must be the same for all
> values. Which unit isn't important, but it must be the same

OOPS - I apologize, I misread the question, I understood the OP to be
saying that x1 was in cm and x2 was in kg. 

What on earth would a correlation mean between two vectors, each of which
is made up of two entirely different measures? (These aren't just
different units, they're measures of entirely different phenomena.)


----------------------------------------------------------------------
Andrew J Perrin - andrew_perrin at unc.edu - http://www.unc.edu/~aperrin
 Assistant Professor of Sociology, U of North Carolina, Chapel Hill
      269 Hamilton Hall, CB#3210, Chapel Hill, NC 27599-3210 USA




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