linear correlation?
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
Secondly, if keep the three large numbers unchanged, just change the three small numbers, the coefficient changes little, this means that the variation of three small numbers is hidden by the three larger numbers. Is there any solution in R to solve this issue?
If you have a vector with the units, you can use it to bring all values
to the same unit
eg (for two different units, if there are more it will be more
complicated)
xu <- c('m','m','m','cm','cm','cm') #units
cor(ifelse(xu=='m',100,1)*x1,ifelse(xu=='m',100,1)*x2)
gruess
joerg
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Joerg Maeder .:|:||:..:.||.:: maeder at atmos.umnw.ethz.ch Tel: +41 1 633 36 25 .:|:||:..:.||.:: http://www.iac.ethz.ch/staff/maeder PhD student at INSTITUTE FOR ATMOSPHERIC AND CLIMATE SCIENCE (IACETH) ETH Z?RICH Switzerland -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._