The current issue of the IRW Newsletter is out and should reach subscribers inboxes during the day. The featuring column is about Uncorrelation and Correlation: The Expectation Values Way.
“Soon or later, those conducting data mining studies will need to deal with uncorrelated and correlated variables. In this issue of the newsletter we use expectation values to differentiate between these two terms. “
The article debunks the common myth that a vanishing correlation coefficient (r = 0) implies that variables have to be random or independent or that are not related at all. Easy-to-follow numerical and graphical examples are used to illustrate this point as well as the difference between uncorrelated and correlated variables.
The Q&A section explains the difference between exponential and power laws and how these can be converted into a linear form. Once linearized, all kind of statistics can be computed (correlation coefficient errors, standard deviations, etc.)
I’m thinking in putting a tutorial online so others can get out of their head the many myths promoted by *certain* SEOs.
Enjoy it.
Looking forward to the tutorial. There is a real need for some instruction on this topic.
Hi, neyne:
Thank you for stopping by. No doubt they are needed.
The first tutorial is on standard errors and is completed. I’m reviewing it now. It explains why we cannot add correlations coefficients to compute a so-called “average” correlation coefficient. Thus, we cannot use such average to compute a standard deviation out of individual coefficients.
One must transform these into Fischer’s z-scores as originally described here:
http://digital.library.adelaide.edu.au/dspace/bitstream/2440/15169/1/14.pdf
http://solarmuri.ssl.berkeley.edu/~schuck/public/manuscripts/Fieller1.pdf
For a given statistical parameter, there is an associated standard error. Using the incorrect definition invalidates any argument or analysis.
BTW. There is a difference between an error and a mistake. Insisting in an incorrect approach to save face is a gross error that destroys credibilities.
The tutorial on standard errors is available now.
http://irthoughts.wordpress.com/2010/06/25/a-tutorial-on-standard-errors/
Enjoy it.